William Q. Walker, Ph.D.

Status and preliminary results for the development of a large format fractional thermal runaway calorimeter (L-FTRC) capable of measuring the total energy release and fractional energy release for Li-ion cells that have greater than 100 Ah capacities.

Fractional thermal runaway calorimetry (FTRC) is a new NASA-developed testing technique designed to quantify the total energy yield of lithium-ion (Li-ion) battery thermal runaway (TR) while simultaneously tallying the fractions of energy released through the cell casing and the ejecta material. Correct representation of the energy yield and the associated division thereof is critical to accurate thermal modeling of battery assembly-level response to thermal runaway events. Here we show how to… Show more

Fractional thermal runaway calorimetry (FTRC) is a new NASA-developed testing technique designed to quantify the total energy yield of lithium-ion (Li-ion) battery thermal runaway (TR) while simultaneously tallying the fractions of energy released through the cell casing and the ejecta material. Correct representation of the energy yield and the associated division thereof is critical to accurate thermal modeling of battery assembly-level response to thermal runaway events. Here we show how to utilize FTRC results in a practical, quick-turnaround, thermal analysis. Show less

When developing this course several years back I asked myself, “What do I think the TFAWS community needs to know about lithium-ion batteries and why should they care?” I think the answers to these questions can be boiled down to the following statements:
1. Lithium-ion (Li-ion) battery electrical performance and efficiency are heavily driven by thermal conditions.
2. Li-ion battery assemblies can experience single cell thermal runaway events which can lead to cell-to-cell propagation;… Show more

When developing this course several years back I asked myself, “What do I think the TFAWS community needs to know about lithium-ion batteries and why should they care?” I think the answers to these questions can be boiled down to the following statements:
1. Lithium-ion (Li-ion) battery electrical performance and efficiency are heavily driven by thermal conditions.
2. Li-ion battery assemblies can experience single cell thermal runaway events which can lead to cell-to-cell propagation; these are thermally driven failure events that can be controlled with effective thermal management systems.
3. Knowledge of BOTH Li-ion battery fundamentals AND traditional thermal design principles are required to develop safe battery assemblies that are both gravimetrically and volumetrically optimized.
This year the Short Course on Lithium-ion Batteries will be presented in a 2-part series. The first portion, “Fundamentals, Battery Safety, and Thermal Runaway,” will focus on educating participants on the fundamental aspects of Li-ion batteries and on battery safety related topics (i.e. thermal runaway, cell-to-cell propagation, safe handling practices, et…). The second portion, “Practical Thermal Simulation Techniques,” will provide participants with a real time demonstration of how to use Thermal Desktop to model of Li-ion battery assemblies. This part of the lesson will cover geometry simplification, mesh development, boundary conditions, and heat loads for both nominal operations (charge and discharge) and for thermal runaway events. Show less

Fractional thermal runaway calorimetry (FTRC) techniques were introduced to examine thermal runaway (TR) behavior of lithium-ion (Li-ion) cells. Specifically, FTRC considers the total energy released vs. the fraction of the total energy that is released through the cell casing vs. through the ejecta material. This device has been expanded to universally support FTRC testing of additional cell types including 21700-format, D-Cell format, and large prismatic format Li-ion cells. The TR behavior… Show more

Fractional thermal runaway calorimetry (FTRC) techniques were introduced to examine thermal runaway (TR) behavior of lithium-ion (Li-ion) cells. Specifically, FTRC considers the total energy released vs. the fraction of the total energy that is released through the cell casing vs. through the ejecta material. This device has been expanded to universally support FTRC testing of additional cell types including 21700-format, D-Cell format, and large prismatic format Li-ion cells. The TR behavior as influenced by cell format, manufacturer, chemistry, capacity, and in situ safety features are described in this presentation. Show less

Fractional thermal runaway calorimetry (FTRC) is a new testing technique designed to examine thermal runaway (TR) behavior of Lithium-ion (Li-ion) cells. FTRC supports the discernment of the total energy released vs. the fraction of the total energy that is released through the cell casing versus through the ejecta materials. This data is critical to both accurate thermal modelling of system level responses to thermal runaway events and to the gravimetric and volumetric optimization of battery… Show more

Fractional thermal runaway calorimetry (FTRC) is a new testing technique designed to examine thermal runaway (TR) behavior of Lithium-ion (Li-ion) cells. FTRC supports the discernment of the total energy released vs. the fraction of the total energy that is released through the cell casing versus through the ejecta materials. This data is critical to both accurate thermal modelling of system level responses to thermal runaway events and to the gravimetric and volumetric optimization of battery thermal management systems. The FTRC testing technique currently supports 18650 format, 21700 format, D-Cell format, pouch-cell format and large prismatic format Li-ion cells. In addition to being able to test multiple cell formats, this testing technique supports a variety of features including rapid turnaround testing capabilities, test apparatus mobility, x-ray transparency for coupling with synchrotron experiments, and multiple trigger techniques (thermal and nail penetration). Participants in this presentation will be educated on the following: (1) FTRC testing techniques, (2) the associated benefits of characterizing thermal runaway with FTRC, and (3) how to use FTRC data to inform thermal analysis and optimization of battery assemblies. Show less

Fractional thermal runaway calorimetry (FTRC) techniques were introduced to examine thermal runaway (TR) behavior of Lithium-ion (Li-ion) cells. Specifically, FTRC considers the total energy released vs. the fraction of the total energy that is released through the cell casing versus through the ejecta material. The original FTRC device was designed to accommodate 18650-format Li-ion cells. This device has been expanded to universally support FTRC testing of additional cell types including… Show more

Fractional thermal runaway calorimetry (FTRC) techniques were introduced to examine thermal runaway (TR) behavior of Lithium-ion (Li-ion) cells. Specifically, FTRC considers the total energy released vs. the fraction of the total energy that is released through the cell casing versus through the ejecta material. The original FTRC device was designed to accommodate 18650-format Li-ion cells. This device has been expanded to universally support FTRC testing of additional cell types including 21700-format, D-Cell format, and large prismatic format Li-ion cells. The TR behavior as influenced by cell format, manufacturer, chemistry, capacity, and in situ safety features are described in this presentation. Show less

Lithium-ion (Li-ion) batteries dominate the global energy storage market.
Unfortunately, safety concerns for the utilization and transportation of these advanced energy storage devices exist due to the inherent possibility of thermal runaway. This chapter provides a detailed description of what Li-ion battery thermal runaway is and how it is characterized. Discussion is given on several high visibility field failure incidents. An introduction is provided on the modeling methods and primary… Show more

Lithium-ion (Li-ion) batteries dominate the global energy storage market.
Unfortunately, safety concerns for the utilization and transportation of these advanced energy storage devices exist due to the inherent possibility of thermal runaway. This chapter provides a detailed description of what Li-ion battery thermal runaway is and how it is characterized. Discussion is given on several high visibility field failure incidents. An introduction is provided on the modeling methods and primary testing techniques used to characterize thermal runaway. Last, a brief discussion is given on future trends and expectations associated with Li-ion battery safety. Show less

Effective thermal management systems, designed to handle the impacts of thermal runaway (TR) and to prevent cell-to-cell propagation, are key to safe operation of lithium-ion (Li-ion) battery assemblies. Critical factors for optimizing these systems include the total energy released during a single cell TR event and the fraction of the total energy that is released through the cell casing versus through the ejecta material. A unique fractional thermal runaway calorimeter (FTRC), designed to… Show more

Effective thermal management systems, designed to handle the impacts of thermal runaway (TR) and to prevent cell-to-cell propagation, are key to safe operation of lithium-ion (Li-ion) battery assemblies. Critical factors for optimizing these systems include the total energy released during a single cell TR event and the fraction of the total energy that is released through the cell casing versus through the ejecta material. A unique fractional thermal runaway calorimeter (FTRC), designed to characterize said critical factors, was utilized to examine the TR behavior of 18650-format Li-ion cells representing a variety of manufacturers, chemistries, capacities, and safety features. Primarily, the impacts of bottom vent (BV) safety features, varied cell casing thickness, and Dreamweaver cellulose based separators were assessed for select cell types. A subset of cells also had an imbedded internal short circuiting (ISC) device to allow examination of TR behavior initiated at lower temperatures (i.e. closer to field failure conditions). The impact of bottom rupture on TR behavior was also examined for experiments that resulted in this non-standard failure mechanism. Statistical analysis of the results for each cell configuration reveals that a lognormal distribution effectively characterizes the variation of total TR energy release. Typically 20%–30% of the total energy yield is released through the cell casing with the remainder through the ejecta material. Higher energy cells tend to exhibit more violent ejections and less predictable TR events. Inclusion of a BV feature reduces the overall severity of the TR event and can increase the predictability. Results also suggest that the magnitude of the TR event may not be directly proportional to the stored electrical energy, but rather has additional dependence on other design and failure mode factors. Show less

Thermal management systems designed to handle the impacts of thermal runaway (TR) are key to safe operation of lithium-ion (Li-ion) batteries. Critical factors for optimizing these systems include the total energy released and the fraction of the total energy that is released through the cell casing versus through the ejecta material. A unique calorimeter, designed to characterize said factors, was utilized to examine the TR behavior of a variety of 18650-format Li-ion cells. Statistical… Show more

Thermal management systems designed to handle the impacts of thermal runaway (TR) are key to safe operation of lithium-ion (Li-ion) batteries. Critical factors for optimizing these systems include the total energy released and the fraction of the total energy that is released through the cell casing versus through the ejecta material. A unique calorimeter, designed to characterize said factors, was utilized to examine the TR behavior of a variety of 18650-format Li-ion cells. Statistical methods were implemented to interpret the data. Show less

This short course provides discussion on three aspects to lithium-ion (Li-ion) batteries that are relevant to the TFAWS community. First an understanding of Li-ion battery fundamentals is provided through discussion centered around the aerospace industry’s choice to use Li-ion batteries, general performance characteristics, and electrochemical reaction basics. Secondly, thermal performance during nominal charge-discharge operations is discussed building from a general energy balance for… Show more

This short course provides discussion on three aspects to lithium-ion (Li-ion) batteries that are relevant to the TFAWS community. First an understanding of Li-ion battery fundamentals is provided through discussion centered around the aerospace industry’s choice to use Li-ion batteries, general performance characteristics, and electrochemical reaction basics. Secondly, thermal performance during nominal charge-discharge operations is discussed building from a general energy balance for representing the local heat generation of a given Li-ion cell. Finally a discussion on understanding the causes and effects of thermal runaway and propagation is presented. The overall goal of the course is to provide participants with an in-depth understanding of the thermal aspects to lithium-ion battery test and analysis. Show less

Effective thermal management systems, designed to handle the impacts of thermal runaway (TR) and to prevent cell-to-cell propagation, are key to safe operation of lithium-ion (Li-ion) battery assemblies. Critical factors for optimizing these systems include the total energy released during a single cell TR event and the fraction of the total energy that is released through the cell casing vs. through the ejecta material. A unique calorimeter was utilized to examine the TR behavior of a… Show more

Effective thermal management systems, designed to handle the impacts of thermal runaway (TR) and to prevent cell-to-cell propagation, are key to safe operation of lithium-ion (Li-ion) battery assemblies. Critical factors for optimizing these systems include the total energy released during a single cell TR event and the fraction of the total energy that is released through the cell casing vs. through the ejecta material. A unique calorimeter was utilized to examine the TR behavior of a statistically significant number of 18650-format Li-ion cells with varying manufacturers, chemistries, and capacities. The calorimeter was designed to contain the TR energy in a format conducive to discerning the fractions of energy released through the cell casing vs. through the ejecta material. Other benefits of this calorimeter included the ability to rapidly test of large quantities of cells and the intentional minimization of secondary combustion effects. High energy (270 Wh kg-1) and moderate energy (200 Wh kg-1) 18650 cells were tested. Some of the cells had an imbedded short circuit (ISC) device installed to aid in the examination of TR mechanisms under more realistic conditions. Other variations included cells with bottom vent (BV) features and cells with thin casings (0.22 μm). After combining the data gathered with the calorimeter, a statistical approach was used to examine the probability of certain TR behavior, and the associated energy distributions, as a function of capacity, venting features, cell casing thickness and temperature. Show less

Effective thermal management systems, designed to handle the impacts of thermal runaway (TR) and to prevent cell-to-cell propagation, are key to safe operation of lithium-ion (Li-ion) battery assemblies. Critical factors for optimizing these systems include the total energy released during a single cell TR event and the fraction of the total energy that is released through the cell casing vs. through the ejecta material. A unique calorimeter was utilized to examine the TR behavior of a… Show more

Effective thermal management systems, designed to handle the impacts of thermal runaway (TR) and to prevent cell-to-cell propagation, are key to safe operation of lithium-ion (Li-ion) battery assemblies. Critical factors for optimizing these systems include the total energy released during a single cell TR event and the fraction of the total energy that is released through the cell casing vs. through the ejecta material. A unique calorimeter was utilized to examine the TR behavior of a statistically significant number of 18650-format Li-ion cells with varying manufacturers, chemistries, and capacities. The calorimeter was designed to contain the TR energy in a format conducive to discerning the fractions of energy released through the cell casing vs. through the ejecta material. Other benefits of this calorimeter included the ability to rapidly test of large quantities of cells and the intentional minimization of secondary combustion effects. High energy (270 Wh kg-1) and moderate energy (200 Wh kg-1) 18650 cells were tested. Some of the cells had an imbedded short circuit (ISC) device installed to aid in the examination of TR mechanisms under more realistic conditions. Other variations included cells with bottom vent (BV) features and cells with thin casings (0.22 μm). After combining the data gathered with the calorimeter, a statistical approach was used to examine the probability of certain TR behavior, and the associated energy distributions, as a function of capacity, venting features, cell casing thickness and temperature. Show less

Expandable habitat technology may offer some strategic benefits for human space exploration applications. These benefits include low launch mass and volume to habitable volume ratios, radiation shielding options, micrometeoroid orbital debris protection, thermal protection and mission cost reduction. To demonstrate the unique capabilities associated with expandable habitats, the National Aeronautics and Space Administration (NASA) partnered with Bigelow Aerospace to develop the Bigelow… Show more

Expandable habitat technology may offer some strategic benefits for human space exploration applications. These benefits include low launch mass and volume to habitable volume ratios, radiation shielding options, micrometeoroid orbital debris protection, thermal protection and mission cost reduction. To demonstrate the unique capabilities associated with expandable habitats, the National Aeronautics and Space Administration (NASA) partnered with Bigelow Aerospace to develop the Bigelow Expandable Activity Module (BEAM). The BEAM was launched on the eighth SpaceX Commercial Resupply Service Mission (CRS-8) and was berthed to the Node 3, aft port, of the International Space Station (ISS) on April 16, 2016. The BEAM is instrumented to collect radiation, vibration and temperature data via an array of sensors. This study summarizes the on-orbit thermal performance of the BEAM and also provides comparison of the collected data to thermal analysis. Conclusions, lessons learned and future work are discussed. Show less

Lithium ion (Li-ion) batteries provide low mass and energy dense solutions necessary for space exploration, but thermal related safety concerns impede the utilization of Li-ion technology for human applications. Experimental characterization of thermal runaway energy release with accelerated rate calorimetry supports safer thermal management systems. ‘Standard’ accelerated rate calorimetry setup provides means to measure the addition of energy exhibited through the body of a Li-ion cell. This… Show more

Lithium ion (Li-ion) batteries provide low mass and energy dense solutions necessary for space exploration, but thermal related safety concerns impede the utilization of Li-ion technology for human applications. Experimental characterization of thermal runaway energy release with accelerated rate calorimetry supports safer thermal management systems. ‘Standard’ accelerated rate calorimetry setup provides means to measure the addition of energy exhibited through the body of a Li-ion cell. This study considers the total energy generated during thermal runaway as distributions between cell body and hot gases via inclusion of a unique secondary enclosure inside the calorimeter; this closed system not only contains the cell body and gaseous species, but also captures energy release associated with rapid heat transfer to the system unobserved by measurements taken on the cell body. Experiments include Boston Power Swing 5300, Samsung 18650-26F and MoliCel 18650-J Li-ion cells at varied states-of-charge. An inverse relationship between state-of-charge and onset temperature is observed. Energy contained in the cell body and gaseous species are successfully characterized; gaseous energy is minimal. Significant additional energy is measured with the heating of the secondary enclosure. Improved calorimeter apparatus including a secondary enclosure provides essential capability to measuring total energy release distributions during thermal runaway. Show less

Conference Presentation

Advanced energy storage and power management systems designed through rigorous materials selection, testing and analysis processes are essential to ensuring mission longevity and success for space exploration applications. Comprehensive testing of Boston Power Swing 5300 lithium-ion (Li-ion) cells utilized by the National Aeronautics and Space Administration (NASA) to power humanoid robot Robonaut 2 (R2) is conducted to support the development of a test-correlated Thermal Desktop (TD) Systems… Show more

Advanced energy storage and power management systems designed through rigorous materials selection, testing and analysis processes are essential to ensuring mission longevity and success for space exploration applications. Comprehensive testing of Boston Power Swing 5300 lithium-ion (Li-ion) cells utilized by the National Aeronautics and Space Administration (NASA) to power humanoid robot Robonaut 2 (R2) is conducted to support the development of a test-correlated Thermal Desktop (TD) Systems Improved Numerical Differencing Analyzer (SINDA) (TD-S) model for evaluation of power system thermal performance. Temperature, current, working voltage and open circuit voltage measurements are taken during nominal charge-discharge operations to provide necessary characterization of the Swing 5300 cells for TD-S model correlation. Building from test data, embedded FORTRAN statements directly simulate Ohmic heat generation of the cells during charge-discharge as a function of surrounding temperature, local cell temperature and state of charge. The unique capability gained by using TD-S is demonstrated by simulating R2 battery thermal performance in example orbital environments for hypothetical extra-vehicular activities (EVA) exterior to a small satellite. Results provide necessary demonstration of this TD-S technique for thermo-electrochemical analysis of Li-ion cells operating in space environments.
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Conference Presentation

Authored chapter in textbook (Rechargeable Lithium Batteries: From Fundamentals to Applications) focusing on the use of lithium and lithium ion batteries used in aerospace.

Lithium-ion batteries (LIBs) are replacing the Nickel-Hydrogen batteries used on the International Space Station (ISS). Knowing that LIB efficiency and survivability are greatly influenced by temperature, this study focuses on the thermo-electrochemical analysis of LIBs in space orbit. Current finite element modeling software allows for advanced simulation of the thermo-electrochemical processes; however the heat transfer simulation capabilities of said software suites do not allow for the… Show more

Lithium-ion batteries (LIBs) are replacing the Nickel-Hydrogen batteries used on the International Space Station (ISS). Knowing that LIB efficiency and survivability are greatly influenced by temperature, this study focuses on the thermo-electrochemical analysis of LIBs in space orbit. Current finite element modeling software allows for advanced simulation of the thermo-electrochemical processes; however the heat transfer simulation capabilities of said software suites do not allow for the extreme complexities of orbital-space environments like those experienced by the ISS. In this study, we have coupled the existing thermo-electrochemical models representing heat generation in LIBs during discharge cycles with specialized orbital-thermal software, Thermal Desktop (TD). Our model’s parameters were obtained from a previous thermo-electrochemical model of a 185 Amp-Hour (Ah) LIB with 1-3 Coulomb (C) discharge cycles for both forced and natural convection environments at 300 Kelvin. Our TD model successfully simulates the temperature vs. depth-of-discharge (DOD) profiles and temperature ranges for all discharge and convection variations with minimal deviation through the programming of FORTRAN logic representing each variable as a function of relationship to DOD. Multiple parametrics were considered in a second and third set of cases whose results display vital data in advancing our understanding of accurate thermal modeling of LIBs.
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Conference Presentation