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Battery thermal barriers are reviewed with regards to extreme fast charging. Present-day thermal management systems for battery electric vehicles are inadequate in limiting the maximum temperature rise of the battery during extreme fast charging. If the battery thermal management system is not designed correctly, the temperature of the cells could reach abuse temperatures and potentially send the cells into thermal runaway. Furthermore, the cell and battery interconnect design needs to be improved to meet the lifetime expectations of the consumer. Each of these aspects is explored and addressed as well as outlining where the heat is generated in a cell, the efficiencies of power and energy cells, and what type of battery thermal management solutions are available in today's market. Thermal management is not a limiting condition with regard to extreme fast charging, but many factors need to be addressed especially for future high specific energy density cells to meet U.S. Department of Energy cost and volume goals. [ABSTRACT FROM AUTHOR]

Battery electric vehicles (BEVs) offer significant potential to reduce the nation's consumption of petroleum based products and the production of greenhouse gases however, their widespread adoption is limited largely by the cost and performance limitations of modern batteries. With recent growth in efforts to accelerate BEV adoption (e.g. the Department of Energy's (DOE) EV Everywhere Grand Challenge) and the age of existing BEV battery technology targets, there is sufficient motivation to re-evaluate the industry's technology targets for battery performance and cost. Herein we document the analysis process that supported the selection of the United States Advanced Battery Consortium's (USABC) updated BEV battery technology targets. Our technology agnostic approach identifies the necessary battery performance characteristics that will enable the vehicle level performance required for a commercially successful, mass market full BEV, as guided by the workgroup's OEM members. The result is an aggressive target, implying that batteries need to advance considerably before BEVs can be both cost and performance competitive with existing petroleum powered vehicles. [ABSTRACT FROM AUTHOR]

Abstract: The high cost of lithium ion batteries is a major impediment to the increased market share of plug-in hybrid electric vehicles (PHEVs) and full electric vehicles (EVs). The reuse of PHEV/EV propulsion batteries in second use applications following the end of their automotive service life may have the potential to offset the high initial cost of these batteries today. Accurately assessing the value of such a strategy is exceedingly complex and entails many uncertainties. This paper takes a first step toward such an assessment by estimating the impact of battery second use on the initial cost of PHEV/EV batteries to automotive consumers and exploring the potential for grid-based energy storage applications to serve as a market for used PHEV/EV batteries. It is found that although battery second use is not expected to significantly affect today''s PHEV/EV prices, it has the potential to become a common component of future automotive battery life cycles and potentially to transform markets in need of cost-effective energy storage. Based on these findings, the authors advise further investigation focused on forecasting long-term battery degradation and analyzing second-use applications in more detail. [Copyright &y& Elsevier]

Abstract: To understand further the thermal abuse behavior of large format Li-ion batteries for automotive applications, the one-dimensional modeling approach formulated by Hatchard et al. [T.D. Hatchard, D.D. MacNeil, A. Basu, J.R. Dahn, J. Electrochem. Soc. 148(7) (2001) A755–A761] was reproduced. Then it was extended to three dimensions so we could consider the geometrical features, which are critical in large cells for automotive applications. The three-dimensional model captures the shapes and dimensions of cell components and the spatial distributions of materials and temperatures, and is used to simulate oven tests, and to determine how a local hot spot can propagate through the cell. In simulations of oven abuse testing of cells with cobalt oxide cathode and graphite anode with standard LiPF6 electrolyte, the three-dimensional model predicts that thermal runaway will occur sooner or later than the lumped model, depending on the size of the cell. The model results showed that smaller cells reject heat faster than larger cells; this may prevent them from going into thermal runaway under identical abuse conditions. In simulations of local hot spots inside a large cylindrical cell, the three-dimensional model predicts that the reactions initially propagate in the azimuthal and longitudinal directions to form a hollow cylinder-shaped reaction zone. [Copyright &y& Elsevier]

This paper summarizes battery thermal modeling capabilities for: (1) an advanced vehicle simulator (ADVISOR); and (2) battery module and pack thermal design. The National Renewable Energy Laboratory’s (NREL’s) ADVISOR is developed in the Matlab/Simulink environment. There are several battery models in ADVISOR for various chemistry types. Each one of these models requires a thermal model to predict the temperature change that could affect battery performance parameters, such as resistance, capacity and state of charges. A lumped capacitance battery thermal model in the Matlab/Simulink environment was developed that included the ADVISOR battery performance models. For thermal evaluation and design of battery modules and packs, NREL has been using various computer aided engineering tools including commercial finite element analysis software. This paper will discuss the thermal ADVISOR battery model and its results, along with the results of finite element modeling that were presented at the workshop on “Development of Advanced Battery Engineering Models” in August 2001. [Copyright &y& Elsevier]

Abstract: A numerical model for cylindrical wound lithium-ion cells, which resolves thermal, electrical and electrochemical coupled physics, is presented in this paper. Using the Multi-Scale Multi-Domain (MSMD) model framework, the wound potential-pair continuum (WPPC) model is developed as a cell domain submodel to solve heat and electron transfer across the length scale of cell dimension. By defining the cell composite as a wound continuum, the WPPC model can evaluate layer-to-layer differences in electrical potential along current collectors, and electric current in the winding direction to investigate the effects of thermal and electrical configurations of a cell design, such as number and location of tabs, on performance and life of a cylindrical cell. In this study, 20-Ah large-format cylindrical cell simulations are conducted using the WPPC model with the number of electrical tabs as a control parameter to investigate how macroscopic design for electrical current transport affects microscopic electrochemical processes and apparent electrical and thermal output. [Copyright &y& Elsevier]

To achieve a successful increase in the plug-in battery electric vehicle (BEV) market, it is anticipated that a significant improvement in battery performance is required to increase the range that BEVs can travel and the rate at which they can be recharged. While the range that BEVs can travel on a single recharge is improving, the recharge rate is still much slower than the refueling rate of conventional internal combustion engine vehicles. To achieve comparable recharge times, we explore the vehicle considerations of charge rates of at least 400 kW. Faster recharge is expected to significantly mitigate the perceived deficiencies for long-distance transportation, to provide alternative charging in densely populated areas where overnight charging at home may not be possible, and to reduce range anxiety for travel within a city when unplanned charging may be required. This substantial increase in charging rate is expected to create technical issues in the design of the battery system and the vehicle's electrical architecture that must be resolved. This work focuses on vehicle system design and total recharge time to meet the goals of implementing improved charge rates and the impacts of these expected increases on system voltage and vehicle components. [ABSTRACT FROM AUTHOR]

The battery technology literature is reviewed, with an emphasis on key elements that limit extreme fast charging. Key gaps in existing elements of the technology are presented as well as developmental needs. Among these needs are advanced models and methods to detect and prevent lithium plating; new positive-electrode materials which are less prone to stress-induced failure; better electrode designs to accommodate very rapid diffusion in and out of the electrode; measure temperature distributions during fast charge to enable/validate models; and develop thermal management and pack designs to accommodate the higher operating voltage. [ABSTRACT FROM AUTHOR]

The safety behavior of lithium-ion batteries under external mechanical crush is a critical concern, especially during large-scale deployment. We previously presented a sequentially coupled mechanical-electrical-thermal modeling approach for studying mechanical-abuse-induced short circuit. In this work, we study different mechanical test conditions and examine the interaction between mechanical failure and electrical-thermal responses, by developing a simultaneously coupled mechanical-electrical-thermal model. The present work utilizes a single representative-sandwich (RS) to model the full pouch cell with explicit representations for each individual component such as the active material, current collector, separator, etc. Anisotropic constitutive material models are presented to describe the mechanical properties of active materials and separator. The model predicts accurately the force-strain response and fracture of battery structure, simulates the local failure of separator layer, and captures the onset of short circuit for lithium-ion battery cells under sphere indentation tests with three different diameters. Electrical-thermal responses to the three different indentation tests are elaborated and discussed. Numerical studies are presented to show the potential impact of test conditions on the electrical-thermal behavior of the cell after the occurrence of short circuit. [ABSTRACT FROM AUTHOR]

In order to better understand the behavior of lithium-ion batteries under mechanical abuse, a coupled modeling methodology encompassing the mechanical, electrical and thermal response is presented for predicting short-circuit under external crush. The combined mechanical-electrical-thermal response is simulated in a commercial finite element software LS-DYNA ® using a representative-sandwich finite-element model, where electrical-thermal modeling is conducted after an instantaneous mechanical crush. The model includes an explicit representation of each individual component such as the active material, current collector, separator, etc., and predicts their mechanical deformation under quasi-static indentation. Model predictions show good agreement with experiments: the fracture of the battery structure under an indentation test is accurately predicted. The electrical-thermal simulation predicts the current density and temperature distribution in a reasonable manner. Whereas previously reported models consider the mechanical response exclusively, we use the electrical contact between active materials following the failure of the separator as a criterion for short-circuit. These results are used to build a lumped representative sandwich model that is computationally efficient and captures behavior at the cell level without resolving the individual layers. [ABSTRACT FROM AUTHOR]

Abstract: A fault leading to a thermal runaway in a lithium-ion battery is believed to grow over time from a latent defect. Significant efforts have been made to detect lithium-ion battery safety faults to proactively facilitate actions minimizing subsequent losses. Scaling up a battery greatly changes the thermal and electrical signals of a system developing a defect and its consequent behaviors during fault evolution. In a large-capacity system such as a battery for an electric vehicle, detecting a fault signal and confining the fault locally in the system are extremely challenging. This paper introduces a fail-safe design methodology for large-capacity lithium-ion battery systems. Analysis using an internal short circuit response model for multi-cell packs is presented that demonstrates the viability of the proposed concept for various design parameters and operating conditions. Locating a faulty cell in a multiple-cell module and determining the status of the fault''s evolution can be achieved using signals easily measured from the electric terminals of the module. A methodology is introduced for electrical isolation of a faulty cell from the healthy cells in a system to prevent further electrical energy feed into the fault. Experimental demonstration is presented supporting the model results. [Copyright &y& Elsevier]