Download or read book Thermal Characterization Multi scale Thermal Modeling and Experimental Validation of Lithium ion Batteries for Automobile Application written by Muhammad Wasim Tahir and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Multiscale Modeling and Characterization for Performance and Safety of Lithium ion Batteries written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Lithium-ion batteries are highly complex electrochemical systems whose performance and safety are governed by coupled nonlinear electrochemical-electrical-thermal-mechanical processes over a range of spatiotemporal scales. In this paper we describe a new, open source computational framework for Lithium-ion battery simulations that is designed to support a variety of model types and formulations. This framework has been used to create three-dimensional cell and battery pack models that explicitly simulate all the battery components (current collectors, electrodes, and separator). The models are used to predict battery performance under normal operations and to study thermal and mechanical safety aspects under adverse conditions. The model development and validation are supported by experimental methods such as IR-imaging, X-ray tomography and micro-Raman mapping.

Download or read book Model Order Reduction of Multi dimensional Partial Differential Equations for Electrochemical thermal Modeling of Large format Lithium ion Batteries written by Guodong Fan and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Lithium ion batteries are considered the state of the art for energy storage in electric and hybrid vehicles. However, there are still several major challenges, such as battery safety, durability and cost, limiting the widespread application of Li-ion batteries in electrified vehicles. Understanding and predicting the chemical and physical processes in Li-ion cells is possible through multi-scale characterization methods. However, ``in-situ" quantification of such processes on a vehicle is not yet achievable due to the absence of direct measurements. Hence, high-fidelity, first-principles models are an essential investigation tool for the prediction of the battery performance and life. While such multi-scale, multi-dimensional first-principles models allow one to characterize the distribution of electrochemical and thermal properties within the cell, they require significant calibration effort and computation time, due to the presence of large scale coupled Partial Differential Equations (PDEs) and nonlinear algebraic equations, ultimately preventing their application to estimation and control algorithm design and verification. This dissertation presents the reduced order electrochemical-thermal models derived from first principles and suitable for real-time simulation, estimation and control design, through the systematic use of projection methods to achieve direct Model Order Reduction (MOR) from linear and nonlinear parabolic PDEs to low-order Ordinary Differential Equations (ODEs). The proposed methodology is applied to an electrochemical-thermal model for the simulation of large-scale Lithium ion battery cells. The resulting reduced-order multi-scale, multi-dimensional model is validated against numerical solutions and experimental data at various input current conditions. The physics-based, ultra-fast modeling tools developed within this research will enable accurate prediction of the electrochemical and thermal distributions within the battery cells, supporting simulation and analysis of performance and remaining usable life of the Li-ion batteries in electrified vehicles.

Download or read book Modeling and Simulation of Lithium ion Power Battery Thermal Management written by Junqiu Li and published by Springer Nature. This book was released on 2022-05-09 with total page 343 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on the thermal management technology of lithium-ion batteries for vehicles. It introduces the charging and discharging temperature characteristics of lithium-ion batteries for vehicles, the method for modeling heat generation of lithium-ion batteries, experimental research and simulation on air-cooled and liquid-cooled heat dissipation of lithium-ion batteries, lithium-ion battery heating method based on PTC and wide-line metal film, self-heating using sinusoidal alternating current. This book is mainly for practitioners in the new energy vehicle industry, and it is suitable for reading and reference by researchers and engineering technicians in related fields such as new energy vehicles, thermal management and batteries. It can also be used as a reference book for undergraduates and graduate students in energy and power, electric vehicles, batteries and other related majors.

Download or read book Thermal and Electro thermal System Simulation 2020 written by Márta Rencz and published by MDPI. This book was released on 2021-01-12 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book, edited by Prof. Marta Rencz and Prof Andras Poppe, Budapest University of Technology and Economics, and by Prof. Lorenzo Codecasa, Politecnico di Milano, collects fourteen papers carefully selected for the “thermal and electro-thermal system simulation” Special Issue of Energies. These contributions present the latest results in a currently very “hot” topic in electronics: the thermal and electro-thermal simulation of electronic components and systems. Several papers here proposed have turned out to be extended versions of papers presented at THERMINIC 2019, which was one of the 2019 stages of choice for presenting outstanding contributions on thermal and electro-thermal simulation of electronic systems. The papers proposed to the thermal community in this book deal with modeling and simulation of state-of-the-art applications which are highly critical from the thermal point of view, and around which there is great research activity in both industry and academia. In particular, contributions are proposed on the multi-physics simulation of families of electronic packages, multi-physics advanced modeling in power electronics, multiphysics modeling and simulation of LEDs, batteries and other micro and nano-structures.

Download or read book Experimental Investigation and Modeling of Lithium ion Battery Cells and Packs for Electric Vehicles written by Satyam Panchal and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The greatest challenge in the production of future generation electric and hybrid vehicle (EV and HEV) technology is the control and management of operating temperatures and heat generation. Vehicle performance, reliability and ultimately consumer market adoption are dependent on the successful design of the thermal management system. In addition, accurate battery thermal models capable of predicting the behavior of lithium-ion batteries under various operating conditions are necessary. Therefore, this work presents the thermal characterization of a prismatic lithium-ion battery cell and pack comprised of LiFePO4 electrode material. Thermal characterization is performed via experiments that enable the development of an empirical battery thermal model. This work starts with the design and development of an apparatus to measure the surface temperature profiles, heat flux, and heat generation from a lithium-ion battery cell and pack at different discharge rates of 1C, 2C, 3C, and 4C and varying operating temperature/boundary conditions (BCs) of 5oC, 15°C, 25°C, and 35°C for water cooling and ~22°C for air cooling. For this, a large sized prismatic LiFePO4 battery is cooled by two cold plates and nineteen thermocouples and three heat flux sensors are applied to the battery at distributed locations. The experimental results show that the temperature distribution is greatly affected by both the discharge rate and BCs. The developed experimental facility can be used for the measurement of heat generation from any prismatic battery, regardless of chemistry. In addition, thermal images are obtained at different discharge rates to enable visualization of the temperature distribution. In the second part of the research, an empirical battery thermal model is developed at the above mentioned discharge rates and varying BCs based on the acquired data using a neural network approach. The simulated data from the developed model is validated with experimental data in terms of the discharge temperature, discharge voltage, heat flux profiles, and the rate of heat generation profile. It is noted that the lowest temperature is 7.11°C observed for 1C-5°C and the highest temperature is observed to be 41.11°C at the end of discharge for 4C-35°C for cell level testing. The proposed battery thermal model can be used for any kind of Lithium-ion battery. An example of this use is demonstrated by validating the thermal performance of a realistic drive cycle collected from an EV at different environment temperatures. In the third part of the research, an electrochemical battery thermal model is developed for a large sized prismatic lithium-ion battery under different C-rates. This model is based on the principles of transport phenomena, electrochemistry, and thermodynamics presented by coupled nonlinear partial differential equations (PDEs) in x, r, and t. The developed model is validated with an experimental data and IR imaging obtained for this particular battery. It is seen that the surface temperature increases faster at a higher discharge rate and a higher temperature distribution is noted near electrodes. In the fourth part of the research, temperature and velocity contours are studied using a computational approach for mini-channel cold plates used for a water cooled large sized prismatic lithium-ion battery at different C-rates and BCs. Computationally, a high-fidelity turbulence model is also developed using ANSYS Fluent for a mini-channel cold plate, and the simulated data are then validated with the experimental data for temperature profiles. The present results show that increased discharge rates and increased operating temperature results in increased temperature at the cold plates. In the last part of this research, a battery degradation model of a lithium-ion battery, using real world drive cycles collected from an EV, is presented. For this, a data logger is installed in the EV and real world drive cycle data are collected. The vehicle is driven in the province of Ontario, Canada, and several drive cycles were recorded over a three-month period. A Thevenin battery model is developed in MATLAB along with an empirical degradation model. The model is validated in terms of voltage and state of charge (SOC) for all collected drive cycles. The presented model closely estimates the profiles observed in the experimental data. Data collected from the drive cycles show that a 4.60% capacity fade occurred over 3 months of driving.

Download or read book Parameter Identification Methodology for Thermal Modeling of Li ion Batteries written by Yatin Khanna and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The major shift in the mobility industry towards electric vehicles requires the development of safer energy storage systems (ESS). Li-ion ESS has been at the forefront of automotive, aerospace, and stationary ESS for power backup applications, albeit it suffers from thermal instability issues, which prompts investigation into the thermal behavior of these systems. Thermal modeling of Li-ion batteries is an essential practice to understand the mechanisms behind heat generation and distribution, and cognizance of the thermal behavior is crucial to developing safer Li-ion batteries and optimal thermal management solutions. However, one of the most significant challenges associated with developing thermal models is parameter identification due to the unique layered construction of a Li-ion cell. The simplest thermal model for a Li-ion battery can require the identification of ten or more unknown parameters. The accuracy of the model depends on the accuracy of the parameter identification process. Thermal models also require electrical models to predict heat generation in the cell, which requires a plethora of unknown parameters to be identified to simulate the electrical behavior of the cell. The overall accuracy of predicted temperature and thermal distribution is dependent on the accuracy of both the electrical and thermal models. The parameter identification for thermal modeling requires extensive experimentation, with its challenges, such as heat propagation to the experimental setup and power cables connecting the cell to the battery cycler. The goal of the research presented in this thesis is to develop an innovative experimental setup, test procedures, and calibration strategy for a lumped-parameter thermal model with the aim of accurately estimating the temperature of the cell and the cell tabs. The research aims at developing a test bench capable of minimizing the heat transfer from the cell to the power cables and the ambient. Two thermal experiments with different boundary conditions are designed that use the test bench for parameter identification and calibration. Finally, the parameters are validated using a standardized duty cycle. An equivalent circuit model is used in the study to estimate the electrical behavior of the cell. The test bench, experiments, and parameter identification, calibration, and validation process developed in the thesis can be used for the thermal characterization of Li-ion cells.

Download or read book Multi scale Modeling of Lithium Ion Batteries written by Ali Hossein Nezhad Shirazi and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rechargeable lithium ion batteries (LIBs) play a very significant role in power supply and storage. In recent decades, LIBs have caught tremendous attention in mobile communication, portable electronics, and electric vehicles. Furthermore, global warming has become a worldwide issue due to the ongoing production of greenhouse gases. It motivates solutions such as renewable sources of energy. Solar and wind energies are the most important ones in renewable energy sources. By technology progress, they will definitely require batteries to store the produced power to make a balance between power generation and consumption. Nowadays, rechargeable batteries such as LIBs are considered as one of the best solutions. They provide high specific energy and high rate performance while their rate of self-discharge is low. Performance of LIBs can be improved through the modification of battery characteristics. The size of solid particles in electrodes can impact the specific energy and the cyclability of batteries. It can improve the amount of lithium content in the electrode which is a vital parameter in capacity and capability of a battery. There exist diferent sources of heat generation in LIBs such as heat produced during electrochemical reactions, internal resistance in battery. The size of electrode's electroactive particles can directly affect the produced heat in battery. It will be shown that the smaller size of solid particle enhance the thermal characteristics of LIBs. Thermal issues such as overheating, temperature maldistribution in the battery, and thermal runaway have confined applications of LIBs. Such thermal challenges reduce the Life cycle of LIBs. As well, they may lead to dangerous conditions such as fire or even explosion in batteries. However, recent advances in fabrication of advanced materials such as graphene and carbon nanotubes with extraordinary thermal conductivity and electrical properties propose new opportunities to enhance their performance. Since experimental works are expensive, our objective is to use computational methods to investigate the thermal issues in LIBS. Dissipation of the heat produced in the battery can improve the cyclability and specific capacity of LIBs. In real applications, packs of LIB consist several battery cells that are used as the power source. Therefore, it is worth to investigate thermal characteristic of battery packs under their cycles of charging/discharging operations at different applied current rates. To remove the produced heat in batteries, they can be surrounded by materials with high thermal conductivity. Parafin wax absorbs high energy since it has a high latent heat. Absorption high amounts of energy occurs at constant temperature without phase change. As well, thermal conductivity of parafin can be magnified with nano-materials such as graphene, CNT, and fullerene to form a nano-composite medium. Improving the thermal conductivity of LIBs increase the heat dissipation from batteries which is a vital issue in systems of battery thermal management. The application of two-dimensional (2D) materials has been on the rise since exfoliation the graphene from bulk graphite. 2D materials are single-layered in an order of nanosizes which show superior thermal, mechanical, and optoelectronic properties. They are potential candidates for energy storage and supply, particularly in lithium ion batteries as electrode material. The high thermal conductivity of graphene and graphene-like materials can play a significant role in thermal management of batteries. However, defects always exist in nano-materials since there is no ideal fabrication process. One of the most important defects in materials are nano-crack which can dramatically weaken the mechanical properties of the materials. Newly synthesized crystalline carbon nitride with the stoichiometry of C3N have attracted many attentions due to its extraordinary mechanical and thermal properties. The other nano-material is phagraphene which shows anisotropic mechanical characteristics which is ideal in production of nanocomposite. It shows ductile fracture behavior when subjected under uniaxial loadings. It is worth to investigate their thermo-mechanical properties in its pristine and defective states. We hope that the findings of our work not only be useful for both experimental and theoretical researches but also help to design advanced electrodes for LIBs.

Download or read book Dynamic Modeling and Thermal Characterization of Lithium ion Batteries written by Khaled I. Alsharif and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lithium-ion batteries have revolutionized our everyday lives by laying the foundation for a wireless, interconnected and fossil-fuel-free society. Additionally, the demand for Li-ion batteries has seen a dramatic increase, as the automotive industry shifts up a gear in its transition to electric vehicles. To optimize the power and energy that can be delivered by a battery, it is necessary to predict the behavior of the cell under different loading conditions. However, electrochemical cells are complicated energy storage systems with nonlinear voltage dynamics. There is a need for accurate dynamic modeling of the battery system to predict behavior over time when discharging. The study conducted in this work develops an intuitive model for electrochemical cells based on a mechanical analogy. The mechanical analogy is based on a three degree of freedom spring-mass-damper system which is decomposed into modal coordinates that represent the overall discharge as well as the mass transport and the double layer effect of the electrochemical cell. The dynamic system is used to estimate the cells terminal voltage, open-circuit voltage and the mass transfer and boundary layer effects. The modal parameters are determined by minimizing the error between the experimental and simulated time responses. Also, these estimated parameters are coupled with a thermal model to predict the temperature profiles of the lithium-ion batteries. To capture the dynamic voltage and temperature responses, hybrid pulse power characterization (HPPC) tests are conducted with added thermocouples to measure temperature. The coupled model estimated the voltage and temperature responses at various discharge rates within 2.15% and 0.40% standard deviation of the error. Additionally, to validate the functionality of the developed dynamic battery model in a real system, a battery pack is constructed and integrated with a brushless DC motor (BLDC) and a load. Moreover, because of the unique pole orientation that a BLDC motor possesses, it puts a pulsing dynamic load on the battery pack of the system. HPPC testing was conducted on the cell that is used in the battery pack to calibrate the model parameters. After the battery model is calibrated, the rotation experiment is conducted at which a battery pack is used to drive a benchtop BLDC motor with a magnetorheological brake as a programable load at varying running speeds. The voltage and current of the battery and the BLDC motor driver are recorded. Meanwhile, the speed and the torque of the motor are recorded. These data are compared to the predicted voltage of the battery pack using the mechanical analogy model. The model estimated the voltage response of a battery pack within 0.0385% standard deviation of the error.

Download or read book 11th Symposium for Fuel Cell and Battery Modelling and Experimental Validation written by kolektiv autorů and published by Librix.eu. This book was released on 2014-03-05 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Analysis of Heat spreading Thermal Management Solutions for Lithium ion Batteries written by Hussam Jihad Khasawneh and published by . This book was released on 2011 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Electrical storage technologies (i.e., batteries) play a ubiquitous role in all facets of modern technologies for applications ranging from very small to very large scale, both stationary and mobile. In the past decade, Li-ion batteries are quickly emerging as the preferred electrical energy storage technology due to the intrinsic power and energy storage density compared to older battery chemistries. All electrochemical batteries are strongly linked to their thermal state: on one hand, their electrical characteristics are strongly dependent on temperature and, on the other hand, their thermal state is a result of both their environmental temperature, but also their electrical usage due to internal heat generation. Furthermore, their life (and potentially safety) is also strongly affected by their thermal state. Li-ion batteries, due to their high electrical power capability and density tend to be used aggressively in many applications, rendering the thermal issues more acute. Finally, Li-ion battery packs (like all packs) are made of many cells interconnected in various series/parallel arrangements in tightly confined spaces. Hence, thermal management solutions need to be implemented for two primary reasons: rejecting the heat generated inside the pack to the environment to avoid high (or unsafe) temperatures leading to premature (or catastrophic) failure and providing a good thermal uniformity among all the cells so that their electrical performance (and aging) in well matched in a pack. This thesis focuses on the thermal modeling of Li-ion packs and the development of passive thermal management solutions for such packs. The thesis first provides an extensive review of the current literature on Li-ion batteries electrical and thermal modeling and current approaches for thermal management solutions of Li-ion packs. This study then focuses on a particular current application using a small Li-ion pack, namely a contractor-grade 36v cordless drill. This particular application was chosen as it encapsulates many of the features of larger automotive packs and represent and leads to an aggressive usage pattern where battery life is always an issue. This pack was experimentally studied to establish typical usage patterns and to measure the thermal and electrical state of the stock pack during such usage. The study then developed and validated a FEM computational pack model in the stock configuration. This experimentally validated models was then used as a proxy to reality to numerically investigate multiple possible configurations of passive thermal management solutions using a high thermal conductivity, Graphite-based heat spreading material to both reduce temperature non-uniformities within the pack and decrease of overall pack temperature (better heat rejection) during aggressive use. Finally, a preliminary experimental validation of one of the promising configurations of heat spreaders was investigated. The work described in this thesis clearly demonstrates that passive heat spreading technology can be very beneficial to reduce thermal stress on batteries and lead to more thermally homogenous packs. Furthermore, this study demonstrated that the investigation of such solutions can be performed with validated thermal FEM models to speed up the development of actual solution and reduce experimental prototype building. Future work will include more configurations, but also experimental investigation of battery life for both thermally managed and unmanaged packs under similar (aggressive) usage patterns. Finally, the conclusions from this study conducted on a cordless power tool are probably equally applicable to large automotive battery packs where life and costs are critical.

Download or read book Electro thermal Modeling of Lithium ion Batteries written by Maryam Yazdan pour and published by . This book was released on 2015 with total page 133 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development and implementation of Lithium-ion (Li-ion) batteries, particularly in applications, requires substantial diagnostic and practical modeling efforts to fully understand the thermal characteristics in the batteries across various operating conditions. Thermal modeling prompts the understanding of the battery thermal behavior beyond what is possible from experiments and it provides a basis for exploring thermal management strategies for batteries in hybrid electric vehicles (HEVs) and electric vehicles (EVs). These models should be sufficiently robust and computationally effective to be favorable for real time applications. The objective of this research is to develop a complete range of modeling approaches, from full numerical to analytical models, as a fast simulation tool for predicting the temperature distribution inside the pouch-type batteries. In the first part of the study, a series of analytical models is proposed to describe distributions of potential and current density in the electrodes along with the temperature field in Li-ion batteries during standard galvanostatic processes. First, a three-dimensional analytical solution is developed for temperature profile inside the Li-ion batteries. The solution is used to describe the special and temporal temperature evolution inside a pouch-type Li-ion cell subjected to the convective cooling at its surfaces. The results are successfully verified with the result of an independent numerical simulation. The solution is also adapted to study the thermal behavior of the prismatic and cylindrical-type nickel metal hydride battery (NiMH) batteries during fast charging processes, which demonstrated the versatility of the model. Afterward, to resolve the interplay of electrical and thermal processes on the heat generation and thermal processes, a closed-form model is developed for the electrical field inside the battery electrodes. The solution is coupled to the transient thermal model through the heat source term (Joulean heat). The results of the proposed multi-physic are validated through comparison with the experimental and numerical studies for standard constant current discharge tests. The model results show that the maximum temperature in the battery arises at the vicinity of the tabs, where the ohmic heat is established as a result of the convergence/divergence of the current streamlines. In the second part of the study, an equivalent circuit model (ECM) is developed to simulate the current-voltage characteristics of the battery during transiently changing load profiles. The ECM that is calibrated by a set of characterization tests collected over a wide range of temperature, then coupled with a numerical electro-thermal model. The validated ECM-based model is capable of predicting the time variation of the surface temperature, voltage, and state of charge (SOC) of the battery during different driving cycles and environmentaltemperatures.

Download or read book Experimental Characterization of Electrodes and Multi Scale Modeling of Swelling Induced Stresses in Lithium ion Batteries written by Priyank Gupta and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Electrochemical thermal Modeling of Lithium ion Batteries written by Mehrdad Mastali Majdabadi Kohneh and published by . This book was released on 2016 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: Incorporating lithium-ion (Li-ion) batteries as an energy storage system in electric devices including electric vehicles brings about new challenges. In fact, the design of Li-ion batteries has to be optimized depending on each application specifications to improve the performance and safety of battery operation under each application and at the same time prevent the batteries from quick degradation. As a result, accurate models capable of predicting the behavior of Li-ion batteries under various operating conditions are necessary. Therefore, the main objective of this research is to develop a battery model that includes thermal heating and is suitable for large-sized prismatic cells used in electric vehicles. This works starts with developing a dual-extended Kalman filter based on an equivalent circuit model for the battery. The dual-extended Kalman filter simultaneously estimates the dynamic internal resistance and state of the charge of the battery. However, the estimated parameters are only the fitted values to the experimental data and may be non-physical. In addition, this filter is only valid for the operating conditions that it is validated against via experimental data. To overcome these issues, physics-based electrochemical models for Li-ion batteries are subsequently considered. One drawback of physics-based models is their high computational cost. In this work, two simplified one-dimensional physics-based models capable of predicting the output voltage of coin cells with less than 2.5% maximum error compared to the full-order model are developed. These models reduce the simulation computational time more than one order of magnitude. In addition to computational time, the accuracy of the physico-chemical model parameter estimates is a concern for physics-based models. Therefore, commercial LiFePO4 (LFP) and graphite electrodes are precisely modelled and characterized by fitting experimental data at different charge/discharge rates (C/5 to 5C). The temperature dependency of the kinetic and transport properties of LFP and graphite electrodes is also estimated by fitting experimental data at various temperatures (10 °C, 23 °C, 35 °C, and 45 °C). Since the spatial current and temperature variations in the large-sized prismatic cells are significant, one-dimensional models cannot be used for the modeling of these prismatic cells. In this work, a resistor network methodology is utilized to combine the one-dimensional models into a three-dimensional multi-layer model. The developed model is verified by comparing the simulated temperatures at the surface of the prismatic cell (consist of LFP as the positive and graphite as the negative electrode) to experimental data at different charge/discharge rates (1C, 2C, 3C, and 5C). Using the developed model the effect of tab size and location, and the current collector thickness, on the electrochemical characteristics of large-sized batteries is evaluated. It is shown that transferring tabs from the edges and the same side (common commercial design) to the center and opposite sides of the cell, and extending them as much as possible in width, lowers the non-uniformity variation in electrochemical current generation.

Download or read book Modeling and Measurements of Thermal Transport in Li ion Based Energy Conversion and Storage Devices written by Krishna Shah (Ph.D.) and published by . This book was released on 2019 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heat transfer is of significant importance in energy conversion and storage devices such as Lithium-ion batteries for its safe operation and performance. Li-ion batteries are considered to be the state of the art among the energy storage devices due to their very high energy density and high power density. However, the safety of Li-ion batteries has become a concern in light of recent incidents, where there have been catastrophic events reported due to overheating of large battery packs. It is imperative to fully understand the nature of thermal transport in Li-ion cells. However, this has not been explored in detail yet. Recent findings have suggested very large thermal conductivity anisotropy in cylindrical Li-ion batteries. In order to make accurate predictions of thermal behavior of the Li-ion cell, it is very important for thermal models to account for such a high degree of anisotropy. In the present work, analytical steady state and transient thermal models have been developed for a cylindrical Li-ion cell. These models can be used as a tool to optimize design parameters and provide directions for further research in improving heat transfer inside a cell for improved safety. A key conclusion from this thermal modeling work is the presence of a very large temperature gradient inside the battery, which indicates poor heat transfer from the core to the surface of a cell, even if cooled aggressively at the surface. This can be explained by a thermal resistor model where the radial conduction resistance is shown to be the rate limiting factor in heat dissipation. From the thermal modeling work, it appears that the heat from the core of the cell isn't being effectively transferred to the surface. This can be due to the large thermal resistance offered by the battery material which the heat has to propagate through. If an axial fluidic channel is provided through the core of the cell, it can significantly improve heat removal from the core of the cell. Fluid flow through an annular channel is a promising strategy for cooling a Li-ion cell. A simplified analytical model is developed to understand this in detail. The model predicts temperature rise inside a cell as a function of average convective heat transfer coefficient over the channel surface and the size of the channel. Gain in terms of higher charge/discharge rate due to the effective cooling is also estimated. Reduction in temperature rise or increase in power density is also compared against the reduction in energy density as a function of channel size. A related fundamental problem of conjugate heat transfer is solved. A classical example of such a problem is flow in a thick tube, which is similar to the problem of the proposed design of a Li-ion battery with an axial fluidic channel. A framework is proposed to solve conjugate heat transfer problem and is demonstrated by solving a couple of commonly occurring conjugate heat transfer problems in reality. The method is validated with a well validated past model and finite element solver. Experimental demonstration of the conceptual design of a Li-ion cell with an annular channel has been done on a thermal test cell. Various cooling strategies, active as well as passive, have been implemented, evaluated and compared. Active cooling is demonstrated by passing air through the channel in the thermal test cell. For passive cooling, a heat pipe/copper rod is inserted in the channel with the tip protruding outside the cell. The results from this work show effectiveness of internal cooling of a Li-ion cell over convectional external cooling. Thermal runaway leads to catastrophic events in energy storage devices with high energy density, such as a pack of Li-ion cells. An experimentally validated thermal model is developed to capture the nonlinear nature of heat generation in a Li-ion cell due to the temperature dependent behavior of exothermic electrochemical reactions. The thermal modeling effort lead to the discovery of a non-dimensional number named as Thermal Runaway Number (TRN) which can help predict onset of thermal runaway and determine thermal stability of a Li-ion cell. This analysis can prove to be crucial to better understand thermal runaway phenomena in Li-ion batteries. Further, thermal modeling to compute temperature in Li-ion cell with temperature dependent heat generation has also been developed. The model has been experimentally validated by simulating temperature dependent heat generation for different values of heat generation parameters. Effect of heat transfer parameters on temperature has also been analyzed.

Download or read book On Mechanical Characterization and Multi scale Modeling of Lithium ion Batteries written by Priyank Gupta and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental Measurements of LiFePO4 Battery Thermal Characteristics written by Scott Mathewson and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A major challenge in the development of next generation electric and hybrid vehicle technology is the control and management of heat generation and operating temperatures. Vehicle performance, reliability and ultimately consumer market adoption are integrally dependent on successful battery thermal management designs. It will be shown that in the absence of active cooling, surface temperatures of operating lithium-ion batteries can reach as high as 50 °C, within 5 °C of the maximum safe operating temperature. Even in the presence of active cooling, surface temperatures greater than 45 °C are attainable. It is thus of paramount importance to electric vehicle and battery thermal management designers to quantify the effect of temperature and discharge rate on heat generation, energy output, and temperature response of operating lithium-ion batteries. This work presents a purely experimental thermal characterization of thermo-physical properties and operating behavior of a lithium-ion battery utilizing a promising electrode material, LiFePO4, in a prismatic pouch configuration. Crucial to thermal modeling is accurate thermo-physical property input. Thermal resistance measurements were made using specially constructed battery samples. The thru-plane thermal conductivity of LiFePO4 positive electrode and negative electrode materials was found to be 1.79 ± 0.18 W/m°C and 1.17 ± 0.12 W/m°C respectively. The emissivity of the outer pouch was evaluated to enable accurate IR temperature detection and found to be 0.86. Charge-discharge testing was performed to enable thermal management design solutions. Heat generated by the battery along with surface temperature and heat flux at distributed locations was measured using a purpose built apparatus containing cold plates supplied by a controlled cooling system. Heat flux measurements were consistently recorded at values approximately 400% higher at locations near the external tabs compared to measurements taken a relatively short distance down the battery surface. The highest heat flux recorded was 3112 W/m2 near the negative electrode during a 4C discharge at 5 °C operating temperature. Total heat generated during a 4C discharge nearly doubled when operating temperature was decreased from 35 °C to 5 °C, illustrating a strong dependence of heat generation mechanisms on temperature. Peak heat generation rates followed the same trend and the maximum rate of 90.7 W occurred near the end of 5 °C, 4C discharge rate operation. As a result, the maximum value of total heat generated was 41.34 kJ during the same discharge conditions. The effect of increasing discharge rate from 1C to 4C caused heat generation to double for all operating temperatures due to the increased ohmic heating. Heat generation was highest where the thermal gradient was largest. The largest gradient, near negative electrode current collector to external tab connection and was evaluated using IR thermography to be 0.632 °C/mm during 4C discharge with passive room temperature natural convection air cooling. Battery designs should utilize a greater connection thickness to minimize both electrical resistance and current density which both drive the dominant mode of heat generation, ohmic heating. Otherwise cooling solutions should be concentrated on this region to minimize the temperature gradient on the battery.