Battery Pack Research Articles

A Novel Self‐Reconfigurable Battery Pack Design with and without Active Cell Balancing

In electric vehicle industry, rechargeable multicell battery packs commonly with fixed configurations are adopted. Such fixed battery configurations have several drawbacks, including limited fault tolerance during unusual operating situations, poor cell state variation management, etc. Thus, this article proposes a self‐reconfigurable battery pack design considering two scenarios: with and without active cell balancing. Herein, the issue of cell state variation is mostly solved by the proposed configuration mode, and further monitoring, control, and protection can be easily appended to accomplish other functionalities, for example, meeting dynamic voltage requirement. Each proposed design is validated by simulation results for a six‐cell polymer lithium‐ion battery pack. The proposed design can maximally utilize the battery's capacity and help to protect cells from over‐charging and over‐discharging as well. This research could be further extended to other application scenarios involving wide‐range dynamic voltage requirements.

Model-free detection and quantitative assessment of micro short circuits in lithium-ion battery packs based on incremental capacity and unsupervised clustering

Timely diagnosis of micro short circuit (MSC) faults is crucial for ensuring the safe operation of lithium-ion battery energy storage systems. Existing diagnostic methods face limitations such as high dependency on battery models, difficulty in determining accurate diagnostic thresholds, or low computational efficiency. This work presents a model-free approach for the detection and quantitative assessment of MSCs in lithium-ion battery packs, with incremental capacity (IC) and unsupervised clustering. First, the IC is extracted from charging voltage data to effectively characterize MSC faults in lithium-ion batteries. Next, principal component analysis is used to map the high-dimensional feature space onto a two-dimensional plane to facilitate fault detection and result visualization. Then, an unsupervised clustering algorithm is employed for anomaly detection to identify MSC cells within the battery pack. For the detected MSC cells, a method based on the maximum charging voltage difference between adjacent cycles is designed to estimate the MSC resistance, quantitatively assessing the severity and evolution stage of the MSC. Experimental results show that the accuracy of MSC detection is 99.17 % and the minimum relative error of short-circuit resistance estimation is 1.20 %, which demonstrates the effectiveness and feasibility of the proposed method.

Adoption of lib (Lithium Batteries) for hybrid propulsion on small passenger vessel and consequences on damage stability

Nowadays the Hybrid Propulsion is a reality, increasing its diffusion. The main principle is the storing of energy in battery packs to provide energy for the propulsion system of the vessel, aiming the fundament of hybrid propulsion is the use of Li-Ion or Li-Po batteries, with high capability of energy storage (MWh). This good capability has the disadvantage of the explosion risk if exposed to heat. The solutions adopted can impact on damage stability. This paper will analyze the aspects connected with hybrid propulsion in small passenger vessels, considering the State of Art of Rules regarding the fire safety and the possible solutions adopted regarding Lithium batteries. The paper refers to the consequences of adoption of new technology of Lithium batteries developed to be used in maritime application, batteries indicated as “LiB”. The paper is not referring to Lithium metal batteries with the Lithium used as metallic anode and all the consequences on fire risks. The paper is not about the risk of fire due to the battery technology, but is related to the consequences on stability of small vessels if, for security reason a large amount of water is used to cool down the battery packs. The paper will consider the case study of a small passenger ship, examining the general arrangement adopted and the position of the batteries, and the consequences caused by the installation on board of the battery packs. The results will show how the fire safety is important and requires special attention, also in consideration of the various possibilities to contain the fire or prevent the risk of explosion. The aim is to give a suggestion for set new standards for firefighting in presence of large batteries and also to focus on possible problems arising in case of fire on hybrid vessels.

Fully Flexible All‐in‐One Electronic Display Skin with Seamless Integration of MicroLED and Hydrogel Battery

AbstractVisualization is a cornerstone in human–computer interaction, evolving from large screens to mobile devices and now to wearable display technology. However, conventional batteries and displays lack the softness and stretchability inherent to human skin. Here, a fully flexible, all‐in‐one electronic display skin by integrating a flexible microLED display, a stretchable circuit, and a Zn|PAM|V2O5 hydrogel battery pack is developed. Vapor‐phase bulk transfer is used to efficiently and accurately transfer 10 000 microLEDs onto a flexible substrate, ensuring high flexibility and ultra‐thin (240 µm). The flexible hydrogel battery pack provides sustainable energy, with a high specific capacity of 331.3 mAh g−1. Additionally, a transparent stretchable circuit board (maximum stretch 40%) is made by 3D printing technology. The skin display exhibited exceptional stretchability and biocompatibility, conforming to movements while maintaining high‐resolution dynamic visual outputs. These innovations pave the way for advanced skin‐implanted displays, promising transformative applications in information interaction, healthcare, and artificial intelligence.

Thermal management of Li-ion battery pack using potting material and air cooling for electric two-wheelers

The increasing popularity of electric two-wheelers has underscored the need for efficient thermal management of Li-ion battery packs, as it is essential for ensuring their optimal performance and safety. This paper presents a detailed study on the application of potting material in combination with air cooling for thermal management in a 3s3p NMC 21700 Li-ion battery pack. The study involved analysing the behaviour of the battery pack through physical testing and validating the findings using simulation with Ansys Fluent 2023 R1 software. The simulation results were then leveraged to predict the battery pack's performance when various potting materials were used. Specifically, the research investigated the impact of thermal conductivity, specific heat, and density on the thermal stability of the battery pack. The outcomes of this study clearly demonstrate the effectiveness of using potting material in conjunction with air cooling to maintain the Li-ion battery pack within the desired temperature range, which is crucial for its reliable operation.In summary, this paper underscores the paramount importance of thermal management in Li-ion battery packs for electric two-wheelers. It offers a comprehensive examination of the combined use of potting material and air cooling, revealing its effectiveness in optimizing battery pack performance and ensuring safety. This research contributes to ongoing efforts aimed at enhancing the performance and safety of Li-ion battery packs in the context of electric two-wheelers.

Analysis of Innovation Trends in Energy Storage Safety Technology based on Patent Data

Against the backdrop of energy transition and the large-scale development of renewable energy, the significance of energy storage technology has become increasingly prominent. Based on the data of invention patents, this paper analyzes the innovation situation of global energy storage safety technology, providing a reference basis for future patent research and industrial planning in the field of energy storage safety. Through the global and Chinese patent application volumes, the research comparatively analyzes the application situations of the main source countries and main applicants of patents, and analyzes the innovation situation of energy storage safety technology by combining research methods such as technical structure comparison and value degree comparison. The study finds that global energy storage safety innovation is in a relatively active period. China takes the leading position in the total amount of patent applications, but the proportion of patents with high value is low, and it still lags behind South Korea and the United States. Currently, the main research directions in this field worldwide mainly include battery monitoring and status monitoring, battery protection, fire detection and alarm, fire extinguishing systems, and battery pack structure design.

Paraffin/graphite/boron nitride composite as a novel phase change material for rapid heat absorption in battery thermal management technology

Phase change material (PCM) cooling is widely employed in the thermal management of compact battery packs. Thermal protection triggered by rapid temperature rise shortens the effective discharge time in high-rate discharge, making it essential to prepare PCM that rapidly absorbs heat at high temperatures. However, research on the thermal absorption performance and insulating properties of PCM at high-rate discharge remains limited. Herein, we innovatively propose a thermally conductive and insulating PCM with a wide phase transition temperature to address the overheating issue in batteries at 7 C, 8 C and 9 C discharge rates. The C236 consists of paraffin (PA236), graphite and boron nitride with a ratio of 6: 2: 2, which achieves outstanding thermal performance with a latent heat of up to 138.0 J/g and a high-volume resistivity of 1.6 × 108 Ω·m. It is found that at a discharge rate of 7 C, the C236 with a thickness of 3 mm effectively maintains the temperature below 80 °C. At discharge rates of 8 C and 9 C, the PCM significantly reduces the battery temperature by 26.9 % and 32.5 %, respectively, highlighting the rapid heat absorption capability at high temperatures. Furthermore, after four cycles at a 9 C discharge rate, the temperature differential of the battery remains below 5 °C. The low-cost PCM provides a new experimental reference for battery thermal management in high-rate discharge, with broad application prospects.

Design of alveolar biomimetic enhanced heat transfer structure for cylindrical lithium battery pack

Aiming to address the issue of thermal runaway in high energy density batteries during high charge and discharge rates, a heat management system for an alveolar-like honeycomb liquid-cooled power battery was designed. This system is inspired by the bionic concept of cell cooling in biological tissues, with cylindrical batteries serving as cells and cooling channels resembling blood vessels. The cooling system for a battery pack consisting of 24 cylindrical cells was designed and implemented. Numerical simulations were conducted to optimize and study the effects of inlet diameter, branch angle, flow rate, and spiral baffle on coolant flow uniformity and temperature distribution within the battery pack. The results indicate that as the inlet diameter of the fractal channel increases from 2 mm to 20 mm, the coolant flow uniformity improves and the pressure drop decreases. However, the influence of inlet diameter diminishes after reaching a certain limit. When the inlet diameter increases from 10 mm to 20 mm, the relative standard deviation of the velocity at the branch outlet decreases only slightly, from 0.9 % to 0.8 %. Increasing the branch angle from 30° to 75° leads to an increase in the relative standard deviation of velocity, from 0.79 % to 1.24 %. Incorporating a spiral baffle into the internal flow channel of honeycomb cooling significantly enhances temperature uniformity within the battery pack while reducing maximum temperature levels considerably. Furthermore, a smaller pitch for the spiral baffle yields better cooling performance for the immersed liquid cooling thermal management system. After optimization, the maximum temperature difference is only 1.27 °C across the surface of the battery pack, achieving a remarkable temperature uniformity level of just 0.11 %.

Analytical Estimation of the C-Rate and Numerical and Experimental Investigation of the EV Battery Pack

Analytical Estimation of the C-Rate and Numerical and Experimental Investigation of the EV Battery Pack

Extending the BESS Lifetime: A Cooperative Multi-Agent Deep Q Network Framework for a Parallel-Series Connected Battery Pack

Extending the BESS Lifetime: A Cooperative Multi-Agent Deep Q Network Framework for a Parallel-Series Connected Battery Pack

Simulation of Battery Thermal Management System for Large Maritime Electric Ship’s Battery Pack

Simulation of Battery Thermal Management System for Large Maritime Electric Ship’s Battery Pack

Study on novel battery thermal management using triply periodic minimal surface porous structures liquid cooling channel

Battery thermal management is a crucial condition for ensuring the safe operation of electric vehicles. The triply periodic minimal surface (TPMS) porous structure boasts high porosity, a large specific surface area, and excellent thermal physical properties. In this study, a novel liquid-cooling channel is designed based on these characteristics. The channel is filled with porous structures and applied in the battery thermal management system (BTMS). Utilizing numerical analysis, compared the cooling performance of liquid-cooling channels filled with different porous structures and investigated the thermal performance of battery modules under diverse factors. The results indicate that the addition of porous structures to the liquid-cooling channel can effectively restrict the maximum temperature of the battery pack and enhance thermal uniformity. Compared to straight tube channel, the Tmax and ΔT of the battery pack with Primitive liquid-cooling structures were reduced by 12.43 % and 8.41 %, respectively. Increasing the volume fraction of the porous structures improves the thermal performance of BTMS, with the best comprehensive performance at a volume fraction of 20 % for the Primitive porous structures. Mass flow rate selection requires attention to the balance between performance and power consumption. Widening the contact angle has the potential to enhance the thermal uniformity of the battery cell, reducing the maximum ΔT of the battery (No.1) from 4.55 °C to 3.46 °C. In addition, the Primitive liquid-cooling structure demonstrates excellent heat dissipation even under extreme temperature conditions, effectively reducing the risk of thermal runaway due to overheating of the battery.

Effect of Battery Pack Stiffness Depending on Battery Cell Types in Cell-to-Pack Technology

Effect of Battery Pack Stiffness Depending on Battery Cell Types in Cell-to-Pack Technology

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.

Kinetics study on inhibiting battery thermal runaway using an inorganic phase change material with a super high thermochemical storage capacity

Lithium-ion batteries are susceptible to fires and explosions due to thermal runaway, a serious safety hazard. This study explores the potential of using hydrated inorganic salt (TCM40) composite phase change materials to prevent thermal runaway in battery packs. TCM40 composites stand out due to their exceptional thermochemical heat storage capacity, which allows them to effectively absorb excess heat during runaway events. The research investigates how thermal conductivity, thermal storage capacity, and cell spacing influence the propagation of thermal runaway. The findings demonstrate that TCM40 composites, with a thermal storage density exceeding 1000 kJ/kg, are significantly more effective in preventing thermal runaway compared to traditional latent heat storage phase change materials with lower capacities. To gain a comprehensive understanding of thermal runaway mitigation, a combined thermal management model was developed. This model integrates a battery thermal runaway model with a kinetic model describing the decomposition of TCM40 composites. The analysis reveals that the high heat absorption capability of TCM40 composites minimizes heat transfer to neighboring cells during thermal runaway. Furthermore, the model provides valuable insights into the synergistic effects of thermal conductivity and heat storage capacity on runaway propagation. This knowledge can be directly applied to design safer battery packs, even for compact configurations where cell spacing is less than 2 mm. This study offers significant advancements in both thermal protection materials and design strategies for lithium-ion battery packs. These advancements have the potential to significantly improve battery system safety and minimize the risk of explosions.

A Novel Battery Temperature-Locking Method Based on Self-Heating Implemented with an Original Driving Circuit While Electric Vehicle Driving: A Numerical Investigation

In extremely cold environments, when battery electric vehicles (BEVs) are navigating urban roads at low speeds, the limited heating capacity of the on-board heat pump system and positive temperature coefficient (PTC) device can lead to an inevitable decline in battery temperature, potentially falling below its permissible operating range. This situation can subsequently result in vehicle malfunctions and, in severe cases, traffic accidents. Henceforth, a novel battery self-heating method during driving is proposed to maintain battery temperature. This approach is ingeniously embedded within the heating mechanism within the motor driving system without any necessity to alter or modify the existing driving circuitry. In the meantime, the battery voltage can be regulated to prevent it from surpassing the limit, thereby ensuring the battery’s safety. This method introduces the dead zone into the space vector pulse width modulation (SVPWM) algorithm to form the newly proposed dSVPWM algorithm, which successfully changes the direction of the bus current in a PWM period and forms AC, and the amplitude of the battery alternating current (AC) can also be controlled by adjusting the heating intensity defined by the ratio of the dead zone and the compensation vector to the original zero vector. Through the Simulink model of the motor driving system, the temperature hysteresis locking strategy, grounded in the field-oriented control (FOC) method and employing the dSVPWM algorithm, has been confirmed to provide controllable and sufficiently stable motor speed regulation. During the low-speed phase of the China Light Vehicle Test Cycle (CLTC), the battery temperature fluctuation is meticulously maintained within a range of ±0.2 °C. The battery’s minimum temperature has been successfully locked at around −10 °C. In contrast, the battery temperature would decrease by a significant 1.44 °C per minute without the implementation of the temperature-locking strategy. The voltage of the battery pack is always regulated within the range of 255~378 V. It remains within the specified upper and lower thresholds. The battery voltage overrun can be effectively avoided.

Fuel Cell Electric Vehicle Hydrogen Consumption and Battery Cycle Optimization Using Bald Eagle Search Algorithm

In this study, the Bald Eagle Search Algorithm performed hydrogen consumption and battery cycle optimization of a fuel cell electric vehicle. To save time and cost, the digital vehicle model created in Matlab/Simulink and validated with real-world driving data is the main platform of the optimization study. The digital vehicle model was run with the minimum and maximum battery charge states determined by the Bald Eagle Search Algorithm, and hydrogen consumption and battery cycle values were obtained. By using the algorithm and digital vehicle model together, hydrogen consumption was minimized and range was increased. It was aimed to extend the life of the parts by considering the battery cycle. At the same time, the number of battery packs was included in the optimization and its effect on consumption was investigated. According to the study results, the total hydrogen consumption of the fuel cell electric vehicle decreased by 57.8% in the hybrid driving condition, 23.3% with two battery packs, and 36.27% with three battery packs in the constant speed driving condition.

Active Cell Balancing Approach for Efficient Battery Management System

With the increasing concern for EV and its battery management system, the effective life and performance of li-ion battery is of utmost importance. The battery cells should be frequently equalized in order to increase the lifetime of battery pack. The conventional method of cell balancing is passive cell balancing where excess energy from cell is dissipated in the form of heat until all the cells are equally charged, causing thermal issues and efficiency in the battery pack. This paper proposes a novel approach for improving the efficiency of battery management systems through active cell balancing using the Kalman filter algorithm thereby overcoming the drawbacks of passive cell balancing. The goal of this paper is to develop a system that can extend the lifespan of batteries by ensuring that each cell is charged and discharged evenly. The proposed system includes an active balancing circuit that uses the Kalman filter algorithm to estimate the state of each battery cell and determine the optimal charging and discharging currents.

Analysis of Early-Stage Behavior and Multi-Parameter Early Warning Algorithm Research for Overcharge Thermal Runaway of Energy Storage LiFePO4 Battery Packs

Overcharging of lithium-ion batteries may lead to severe thermal runaway (TR) incidents, resulting in significant economic losses and safety hazards. Therefore, it is crucial to research early warning methods for TR behavior in overcharged lithium batteries. This study initially conducted overcharging experiments on LiFePO4 battery packs under different initial charging states and charging rates, analyzing variations in temperature, voltage, and inter-group pressure during overcharging. The TR process was divided into three stages: non-overcharged, early, and middle. Based on this, temperature change rate, pressure change rate, and voltage were extracted as input feature parameters, and the Mean Shift algorithm was employed for stage identification and classification of overcharging experiments on LiFePO4 battery packs. According to experimental results, the algorithm achieved an accuracy of over 96% in stage identification and classification of TR in overcharged lithium batteries, accurately determining the current stage of TR and providing a reliable and effective solution for preventing TR in overcharged lithium batteries.

Investigating the impact of battery arrangements on thermal management performance of lithium-ion battery pack design

The working temperature is one of the key factors affecting the efficiency and safety performance of automotive power batteries. Current battery pack design primarily focuses on single layout configurations, overlooking the potential impact of mixed arrangements on thermal management performance. This study presents a module-based optimization methodology for comprehensive concept design of Lithium-ion (Li-ion) battery pack. Firstly, the arrangement modules is optimized and performed using particle swarm optimization algorithms considering various arrangement layout (i.e. rectangular, diamond, and staggered arrangements) by taking the intercell spacing and maximum temperature of the modules as design objectives. Secondly, the battery pack configuration design is performed employing a neural network model reflect diverse battery module configurations within the pack, exploring their impact on thermal management performance. The hybrid battery arrangement effectively improves thermal management, and the module spacing helps to enhance heat dissipation. The staggered arrangement has a greater impact on the heat dissipation performance of the battery pack, but the spacing between different modules varies with the position of the modules. When all configuration schemes are staggered modules, the optimal range of the spacing between modules is between 6 and 7 mm. However, the study observes a non-linear relationship between module spacing and the maximum temperature difference within the battery pack. While increasing module spacing initially decreases temperature differences, it eventually reverses, suggesting that spacing alone may not consistently enhance thermal management. Validation with a lithium-ion battery pack case study demonstrates the method’s effectiveness, providing valuable knowledge for future cell and pack designs that employ different battery cell arrangements and diverse cooling strategies.