Automotive Battery Research Articles

Reducing Energy Consumption and Greenhouse Gas Emissions of Industrial Drying Processes in Lithium-Ion Battery Cell Production: A Qualitative Technology Benchmark

As the world’s automotive battery cell production capacity expands, so too does the demand for sustainable production. Much of the industry’s efforts are aimed at reducing the high energy consumption in battery cell production. A key driver is electrode drying, which is currently performed in long ovens using large volumes of hot air. Several drying technologies from other industries could reduce energy consumption and greenhouse gas emissions if successfully applied to battery cell production. High process and quality requirements must be met when adapting these technologies for battery cell production. Evaluating the technologies against these requirements is difficult due to the technological novelty of this industry and the associated lack of data. Furthermore, the significant differences in drying technologies render a comparison even more challenging. One objective of this study was to evaluate drying technologies and identify those that could be best adapted to lithium-ion battery cell production. Near-infrared and laser drying were found to be the best in terms of energy efficiency, cost savings and other parameters. Another aim was to analyse, in more detail, the technological challenges and the advantages and disadvantages of the top-ranked drying technologies. Finally, the saving potential for greenhouse gas emissions of near-infrared and laser drying was calculated for a global production scenario of LIB cells in 2030. The saving potential in this scenario would amount to 2.63 million metric tonnes (Mt) CO2eq per year if near-infrared drying was applied in all global LIB cell production facilities within the mentioned scenario and 1.47 million Mt CO2eq per year for laser drying.

Multivariable analysis of vortex generator-aided heat transfer enhancement for 18650 battery thermal management system

Currently, electric vehicles and hybrid cars have emerged as global solutions to replace internal combustion engine vehicles, with lithium-ion batteries being the most widely chosen option due to their low discharge rates and high energy density. Air-cooling systems, recognized for their cost-effectiveness and stability, are extensively employed in the thermal management systems of automotive batteries. However, conventional air-cooling models exhibit drawbacks in uniformly cooling battery packs. In this study, a numerical investigation is conducted to explore the enhanced cooling heat transfer facilitated by a vortex generator in the air-cooled battery thermal management system. The heat generation and transfer of a battery pack are analyzed using the experimentally validated 2C discharge heat dissipation model for batteries. The assessment focuses on the impact of a vortex generator on the heat transfer performance of a series-connected battery pack. The results indicate that fluid mixing, boundary layer modification, and flow instability are the primary factors contributing to enhanced heat transfer. Through the utilization of orthogonal experimental design and fuzzy grey relational analysis, the influence of three parameters (vortex generator position, angle of attack, and fin height) on thermal performance was systematically analyzed. The analysis reveals that the vortex generator position exerts the most significant impact on the heat transfer index, followed by height, with the angle having the least effect. Nusselt number and entropy generation were chosen as optimization indicators for a comparative analysis of enhancing heat transfer with and without optimized vortex generator assistance. The research results demonstrate that the optimal scenario occurs when entropy generation is minimized, resulting in a 56.4 % reduction in temperature difference (2.66 K) and a 12.1 % decrease in the maximum temperature (2.75 K). This study provides valuable guidance for further optimizing battery thermal management.

Recovery of Residual Lead from Automotive Battery Recycling Slag Using Deep Eutectic Solvents.

In this study, we address the ecological challenges posed by automotive battery recycling, a process notorious for its environmental impact due to the buildup of hazardous waste like foundry slag. We propose a relatively cheap and safe solution for lead removal and recovery from samples of this type of slag. The analysis of TCLP extracts revealed non-compliance with international regulations, showing lead concentrations of up to 5.4% primarily in the form of anglesite (PbSO4), as detected by XRF/XRD. We employed deep eutectic solvents (DES) as leaching agents known for their biodegradability and safety in hydrometallurgical processing. Five operational variables were systematically evaluated: sample type, solvent, concentration, temperature, and time. Using a solvent composed of choline chloride and glycerin in a 2:1 molar ratio, we achieved 95% lead dissolution from acidic samples at 90 °C, with agitation at 470 rpm, a pulp concentration of 5%, and a 5 h duration. Furthermore, we successfully recovered 55% of the lead in an optimized solution using an electrowinning cell. This research demonstrates the ability of DES to decontaminate slag, enabling compliance with regulations, the recovery of valuable metals, and new possibilities for the remaining material.

Application of power battery under thermal conductive silica gel plate in new energy vehicles

This study aims to improve the performance of automotive battery thermal management systems (BTMS) to achieve more efficient heat dissipation and thus reduce hazards during driving. Firstly, the research parameters and properties of composite thermally conductive silicone materials are introduced. Secondly, the heating principle of the power battery, the structure and working principle of the new energy vehicle battery, and the related thermal management scheme are discussed. Finally, the research results are presented from the experimental test and controller design. In addition, to achieve the research goal, the composite thermally conductive silica gel plate (CSGP) material is studied in detail and parametrically analyzed, and the heating mechanism of the power battery is discussed in depth. The temperature characteristics after adding CSGP are experimentally tested, and the controller of the BTMS of the new energy vehicle is designed, including hardware circuits and software modules. The findings show that the temperature characteristics of the battery module have obvious limitations without CSGP. When the battery module operates at a 4C magnification, the temperature exceeds the safety threshold by 38.4%, with particular potential safety risks. Then, the maximum temperature of the battery module with CSGP can be controlled within 50 °C, and the temperature characteristics are prominently improved. Lastly, the controller of the BTMS is tested, and the results reveal that it has remarkable voltage recovery ability. According to the research results, the performance of automotive BTMS can be significantly improved, and better heat dissipation can be effectively achieved by adding CSGP. This helps reduce the hazards of driving. Moreover, the designed controller performs well in voltage recovery, providing solid theoretical support for further developing the CSGP battery management system.

The role of oxygen in automotive grade lithium-ion battery cathodes: an atomistic survey of ageing.

The rising demand for high-performance lithium-ion batteries, pivotal to electric transportation, hinges on key materials like the Ni-rich layered oxide LiNixCoyAlzO2 (NCA) used in cathodes. The present study investigates the redox mechanisms, with particular focus on the role of oxygen in commercial NCA electrodes, both fresh and aged under various conditions (aged cells have performed >900 cycles until a cathode capacity retention of ∼80%). Our findings reveal that oxygen participates in charge compensation during NCA delithiation, both through changes in transition metal (TM)-O bond hybridization and formation of partially reversible O2, the latter occurs already below 3.8 V vs. Li/Li+. Aged NCA material undergoes more significant changes in TM-O bond hybridization when cycling above 50% SoC, while reversible O2 formation is maintained. Nickel is found to be redox active throughout the entire delithiation and shows a more classical oxidation state change during cycling with smaller changes in the Ni-O hybridization. By contrast, Co redox activity relies on a stronger change in Co-O hybridization, with only smaller Co oxidation state changes. The Ni-O bond displays an almost twice as large change in its bond length on cycling as the Co-O bond. The Ni-O6 octahedra are similar in size to the Co-O6 octahedra in the delithiated state, but are larger in the lithiated state, a size difference that increases with battery ageing. These contrasting redox activities are reflected directly in structural changes. The NCA material exhibits the formation of nanopores upon ageing, and a possible connection to oxygen redox activity is discussed. The difference in interaction of Ni and Co with oxygen provides a key understanding of the mechanism and the electrochemical instability of Ni-rich layered transition metal oxide electrodes. Our research specifically highlights the significance of the role of oxygen in the electrochemical performance of electric-vehicle-grade NCA electrodes, offering important insights for the creation of next-generation long-lived lithium-ion batteries.

A Study on the Cradle-to-Gate Environmental Impacts of Automotive Lithium-ion Batteries

Several factors are influencing the spread of Electric Vehicles (EVs) in the automotive market. However, while battery-electric vehicles emit no tailpipe emissions, the manufacturing phase, particularly the manufacturing of the battery packs, can have significant environmental impacts. In addition, as the EV market expands, there will be a significant increase in demand for critical materials used in lithium-ion batteries, such as lithium, cobalt, and nickel. These materials are essential for producing high-performance batteries, and their global demand is expected to rise rapidly to meet the demands of the expanding market. This paper investigates the main challenges that need to be tackled to reach a sustainable path in the battery industry. A cradle-to-gate boundary is set to focus on raw material extraction, production of precursors, cell and module production, and battery pack assembly. In addition, because 7.8 million tons of EV batteries per year are expected to reach the end-of-life phase by 2040, a brief overview of the recycling issue is provided to investigate the potential usage of recycled material in the early stages of battery production.

The impact of the degree of automation on the configuration of a car battery assembly line

This paper presents the concept of an automotive battery assembly line. The line includes in its structure fully and semi-automated assembly sockets, as well as manual assembly sockets. The transport between the sockets is carried out using an AGV autonomous trolley system. The selection of the assembly process execution method was based on an analysis of the technical feasibility of the process as well as an analysis of the occupation time of individual assembly stations. The resulting line structure indicates to what extent the automation of the assembly process contributes to a change in material flow and influences the way the process is carried out, including a variety of technical means used. The paper presents an analysis of the use of particular workstations. This analysis was used to optimise the flow of the component assembly line. Maximum utilisation of the resources involved in the production process was used as a criterion for optimisation.

Laser-based battery pack disassembly: a compact benchmark analysis for separation technologies

The global decarbonization will have to be driven by the e-mobility sector to achieve the climate goals. End-of-life battery packs therefore need to be recycled efficiently and sustainably so that a cost-competitive circular economy can be adopted. In current process approaches, once the battery is discharged, disassembly is typically performed manually in a process that is not automated and dangerous to workers. To disassemble, first the battery cover must be removed, whereby current technological approaches focus on screw connections, which are difficult to loosen due to their condition after many years in the vehicle and cause poor automation capability. Another alternative is to mechanically mill the battery cover, which creates chips inside the battery pack that can cause short circuits. Waterjet cutting, which is also a process approach, faces the challenge of water getting into the battery pack, which can also lead to short circuits. Therefore, there is a need for new technological approaches which can dismantle an automotive battery pack productively with enhanced safety standards for workers and batteries. For this purpose, this paper performs a compact benchmark analysis of different separation technologies to identify initial potentials and challenges for laser-based disassembly of automotive battery packs.

Fast and Energy-Efficient Compound Self-Heating of Automotive Batteries Based on Electrochemical-Thermal-Stress Aging Model

Fast and Energy-Efficient Compound Self-Heating of Automotive Batteries Based on Electrochemical-Thermal-Stress Aging Model

Amplitude–Frequency Decoupled Heater and Integrated Strategies for Automotive Batteries Based on Inverter and Motor

Amplitude–Frequency Decoupled Heater and Integrated Strategies for Automotive Batteries Based on Inverter and Motor

An Evaluation of the Environmental Impacts and Economic Performance of Automotive Battery Recycling: Bangladesh Perspective

An Evaluation of the Environmental Impacts and Economic Performance of Automotive Battery Recycling: Bangladesh Perspective

Experimental Analysis of Thermal Runaway Energy Release of an Automotive Li-Ion Battery Cell

Thermal runaway (TR) reactions of lithium ion cells pose a particular risk to the safety of battery systems. Beside the energy remaining in the cell body, particles and gases exiting the cell during the venting process cause major thermal load for adjacent cells and further system components [1]. In addition, high energy particles can act as an ignition source in the presence of ignitable venting gases and oxygen [2]. Therefore, measurements minimizing the risk of thermal propagation (TP) caused by venting ejecta material and the ignition of combustible gases are introduced on system level. For the dimensioning of the measures, the energy transported by venting particles and gases is identified as a crucial parameter. Depending on the amount of transported energy, the gas cooling distance as well as the complexity of the particle separation structure differ. Simulation methods are used to evaluate the effectiveness of such system measures. More information is needed regarding energy release to accurately predict the system behavior in simulations and to use them as a tool for design.Introducing a novel approach for TR tests enables the determination of the energy remaining in the cell body, separated from the energy transported by venting ejecta. The test setup combines a calorimeter combined with a cyclone separator placed inside an autoclave reactor. The TR energy release of 156 Ah prismatic lithium ion cells have been analyzed using the setup. Venting particles and gases transported a main part of the released energy out of the cell during the TR. Using an analytical approach, the energy transferred to the calorimeter is calculated. The obtained data can be used for validating simulation models for predicting the impact of venting reactions on TP.

New Method for Designing Robust External Short-Circuit Protection Systems at Different Scales

External short circuit is one of the failure modes of Li-ion and other batteries that potentially leads to serious damage such as, overheating and/or thermal runaway. Therefore in this work we test and analyse the short circuit behaviour of different system sizes from coin cells, 10Ah pouch cells and upto large scale automotive high voltage battery packs. It was found that the complex short circuit behavior can be described by 3 regions independently of the size of the battery. In the first region 274C-rate is observed which is mainly governed by the cell's double and diffusion layer discharge. In the second region, the current drops significantly to 50–60C-rate where mass transport becomes the current limiting factor. The maximum temperature is reached and cell rupture, venting and electrolyte leakage may occur. Then the current stabilizes at the maximum mass transport region independently of the external short circuit. This complex time behavior need to be covered by different fuses, circuit breaker and intelligent battery management system. The protection strategy depends on several factors, which makes the design process complex. We introduce the normalized resistance ratio which allows the comparison of external shorts with different external resistance and cells and with different capacities. We demonstrate that the estimation of the maximum external short circuit current derived in this work is more accurate than other calculations at different levels. Furthermore we developed and present a generalized visualisation of the full time-current window which potentially help scientists and engineers to design more robust external short circuit protection systems. With this method we also demonstrate that the currently used external short circuit design methods may potentially lead to unsafe regions especially in the soft short region. We also propose a testing protocol which can be applied in standards, regulations without jeopardizing the safety of testing personnels and infrastructure.

(Invited) Sensor Integration in Lithium-Ion Cells from a Systems Perspective

The cell temperature is a critical factor that impacts performance, safety and longevity of batteries. For the optimum operating strategy, therefore, maximum and minimum cell temperature must be available to the BMS at all times. This is a challenge, however, because typical automotive batteries use more than a hundred cells and the cells themselves do not exhibit a homogeneous temperature.For this reason, it was and is particularly important in the development of lithium-ion batteries to measure the temperatures at the relevant points - and thus often also inside the cells themselves.In the first part, an overview of the current state of research on cell-internal temperature measurement will be given and the efforts to transfer these approaches into application will be further discussed. In particular, the technical requirements at the system level will be discussed, but also the difficulties of industrialization.In addition to the integration of sensors, the determination of temperature from already existing variables such as cell voltage and current has already been described in many approaches. In particular, the application of impedance spectroscopy has reached a level that can be described as ready for industrialization. After an overview of the current state of research, the requirements for application in the target system will be addressed and the necessary further research is discussed.

Needle penetration studies on automotive lithium-ion battery cells: Influence of resistance between can and positive terminal on thermal runaway

Thermal runaway (TR) can be initiated by the heat dissipated from an internal short circuit (ISC). In prismatic cells, a crucial type of ISC is located between the cell can on positive potential and the first anode layer. To enhance the safety, the potential of the can could be adjusted by increasing the ISC resistance, i.e., realizing a floating can, whereas a universal automotive prismatic cell has a can on potential in contrast. This work demonstrates that the floating can mitigates the ISC current and possibly prevents ISC from leading to TR using an advanced needle penetration test. Moreover, the ISC current was quantitatively measured, proving that there is no significant ISC current between floating can and outmost anode, while the ISC with can on potential can cause TR. To demonstrate that such difference originates only from the increased resistance, the equivalence in thermal behaviors between the two types of cans was analyzed by a heat-wait-seek test in an accelerating rate calorimeter. This work provides not only a guidance on designing a safer prismatic cell but also a prospect how the optimized needle penetration test can bring a deeper insight into the internal processes of Lithium-ion cells during mechanical abuse.

Thermal runaway propagation in automotive lithium-ion batteries with NMC-811 and LFP cathodes: Safety requirements and impact on system integration

Thermal runaway propagation mitigation is a prerequisite in battery development for electric vehicles to meet legal requirements and ensure vehicle occupants’ safety. Thermal runaway propagation depends on many factors, e.g., cell spacing, intermediate materials, and the entire cell stack setup. Furthermore, the choice of cell chemistry plays a decisive role in the safety design of a battery system. However, many studies considering cell chemistry only focus on the cell level or neglect the energetic impacts of safety measures on system integration. This leads to a neglect of the conflict of objectives between battery safety and energy density. In this article, a comprehensive analysis of the thermal runaway propagation in lithium-ion batteries with NMC-811 and LFP cathodes from a Mini Cooper SE and Tesla Model 3 SR+ is presented. The focus is set on the identification of differences in battery safety, the derivation of safety requirements, and the evaluation of their impact on system integration. A comparative analysis identified significantly higher safety requirements for Graphite | NMC-811 than for Graphite | LFP cell chemistries. Regarding cell energy, thermal runaway reaction speed is nine times faster in NMC-811 cells and five times faster considering the whole propagation interval than LFP cells. However, since LFP cell chemistries have significantly lower energy densities than ternary cell chemistries, it must be verified whether the disadvantages in energy density can be compensated by advanced system integration. An analysis of cell-to-pack ratios for both cell chemistries has revealed that, based on average values, the gravimetric disadvantages are reduced to 16%, and the volumetric disadvantages can be completely compensated for at the pack level. However, future research should further focus on this issue as an accurate safety-related design depending on cell chemistry could enable a cost–benefit evaluation under the constraints of safety standards in the development of batteries for electric vehicles.

Internal Heating Techniques for Lithium-Ion Batteries at Cold Climates: An Overview for Automotive Applications

Lithium-ion (Li-ion) batteries suffer from substantial capacity and power degradation at low temperatures, severely deteriorating the performance of battery-based transportation electrification. To overcome this issue, different preheating techniques have been proposed to recover the performance of Li-ion batteries in cold climates. Among these, internal heating schemes are more promising than traditional conductive and convective approaches owing to their superiorities in terms of high efficiency, rapid speed, and uniform temperature distribution. This paper reviews various internal heating methodologies developed in recent years for Li-ion batteries, including mutual pulse current heating, alternating current heating, compound heating, and all-climate-battery based heating. Specifically, the effects of low temperatures on Li-ion batteries are first outlined in terms of cell performance and electrochemical characteristics. Then, the heat generation mechanism during internal heating is briefly described, based on which the internal temperature monitoring methods are also investigated considering the temperature gradient. Next, a comprehensive literature survey on different internal heating schemes with their basic principles, benefits, and drawbacks is presented. Finally, future trends of internal heating methods to benefit automotive battery performance are discussed in terms of key technologies, promising opportunities, and challenges.

Comprehensive Analysis on Power Factor Correction Circuit

With the development of industrial power electronics, the current era can be called the "world energy era". Energy has never been more important, especially with the growing demand for today's "green" energy sources. power factor correction circuits have become an integral part of most current AC voltage input power applications, whether it is automotive battery power, portable energy storage (such as power banks), traditional server power, or lighting systems. However, the basic principles of power factor correction converters are rarely described in detail. This paper will summarize and illustrate the basic principle of the power factor correction circuit, and first introduce the research background of power factor correction technology; At the same time, three operating modes of power factor correction circuit are analyzed: continuous on-mode (CCM), critical on-mode (CRM) and discontinuous on-mode (DCM), and their advantages and disadvantages are to be further discussed. In addition, the PFC converters with optimized topology and excellent performance will be introduced, and the application prospect and prospect of three-phase PFC converters will be presented.

Shell Shape Influence on Latent Heat Thermal Energy Storage Performance during Melting and Solidification

Phase-change materials have various applications across industries from thermal energy storage through automotive battery temperature management systems to thermal stabilisation. Many of these applications are shell and tube structures with different shell shapes. However, it is not yet known how the shape of the shell affects the melting, solidification times, and heat transport processes in such structures. To fill this research gap, seventeen shell shapes/orientations were compared using a simulation study. The well-known and validated enthalpy porosity algorithm implemented in the Fluent 2021R2 software was used. The numerical calculations were preceded by the measurement of thermal conductivity, phase change enthalpy, and specific heat during melting and solidification of the phase-change material. The shortest melting time was achieved for a semi-circular shell shape in the downward position, which was 44% shorter than the reference circular case. The shortest solidification times were recorded for an isosceles trapezium in an upward orientation relative to the reference circular case. Therefore, it is possible to significantly reduce the melting time in shell-and-tube systems as a result of the appropriate selection of the shell shape.

Development of a High-Frequency Test System to Study the Wear of Ultrasonic Welding Tools

In current automotive lithium-ion battery manufacturing, Ultrasonic Metal Welding (USMW) is one of the major joining techniques due to its advantages in welding multiple thin sheets of highly conductive materials. The sonotrode, serving as the welding tool, transmits high-frequency oscillation to the joining parts. Due to the high frequency of thermal-mechanical loading, the knurl pattern on the sonotrode wears with an increasing number of welds, which significantly influences the welding process, resulting in poor joint quality. In this study, a high-frequency test system was developed to investigate the wear mechanisms of the sonotrode. Based on the comparable relative motion to the welding process, the thermal-mechanical loadings on the contact area were analyzed. As the oscillation amplitude of the sonotrode increased, the estimated frictional force between the sonotrode and the copper counter body remained constant, while an increase in the sliding distance was observed in the contact area. Temperature development showed a strong correlation with mechanical loading. A first approach of continuous testing was performed but was limited due to the failure of the copper counter body under ultrasonic stimulation.