Name: in situ gas analysis and fire characterization of lithium-ion cells during thermal runaway using an environmental chamber
Uploaded: 2023-03-31T15:00:00.000+00:00
Duration: 8 min 42 s
Description: Watch this Scientific Journal Video about In Situ Gas Analysis and Fire Characterization of Lithium-Ion Cells During Thermal Runaway Using an Environmental Chamber at JoVE.com

This study is supported by the UL Research Institutes. All battery cells in this work were conditioned and prepared in Prof. Chris Yuan&#39;s lab at Case Western Reserve University (CWRU). The test chamber is on loan to CWRU from NASA Glenn Research Center. We received tremendous support on the FTIR gas analyzer from a former PhD student, Dr. Yumi Matsuyama at CWRU, and technical support on the H2 sensor from Jeff Tucker, Brandon Wicks, and Brian Engle from Amphenol Advanced Sensors. We sincerely appreciate the support from Pushkal Kannan and Boyu Wang at CWRU. We would also like to acknowledge the technical discussions with Alexandra Schraiber from UL Solutions.

1. Startup of the FTIR gas analyzer
NOTE: The procedures can be different for different brands and models of the FTIR gas analyzer. The following procedure is for the specific gas analyzer used in this work.
<ol>
	<li>Install a new filter or a clean filter (i.e., one that has been cleaned in an ultrasonic bath) in the filter/valve unit (see Figure 1 and Figure 2).</li>
	<li>Open the valve of the nitrogen cylinder connected to the gas analyzer (see Figure 2). Adjust the nitrogen flow rate to 150-250 cc/min. 
	NOTE: This is to prepare for the N2 purging during the pre/post-test cleaning of the gas analyzer.</li>
	<li>Follow the FTIR startup procedure described in the manufacturer manual, &#34;FTIR and PAS Pro for the FTT Smoke Density Chamber Standard Operating Procedure&#34;24, Version 3.1. 
	&#8203;NOTE: While the FTIR is running, the gas line between the FTIR and the chamber (see Figure 2) is maintained at 180 &#176;C to prevent gas condensation. Be careful not to touch the heated line and the filter/valve unit.</li>
</ol>
2. Cell preparation
<ol>
	<li>Record the date, time, SOC, test participants, test number, cell manufacturer, cell format, and cell model number on an experiment log sheet.</li>
	<li>Measure and record the initial voltage and mass of the cell (with a precision of 0.01 g) on the experiment log sheet.</li>
	<li>Attach heating tape (1 in x 2 in, 20 W/in2) to the center of the cell and take a picture of the cell with the heating tape. Ensure that the heating tape wires point toward the negative side of the cell (see Figure 3).</li>
	<li>Attach three thermocouples (K-type with a probe diameter of 0.02 in, length of 12 in) to the cell surface using high-temperature resistant tape, one near the positive terminal, one in the middle, and one at the bottom near the negative terminal of the cell, all located 5 mm away from the edge of the heating tape (see Figure 3A). Use the thermocouple near the positive terminal to control the heating rate through the PID. After installing the thermocouples, take a picture of the cell with a ruler to confirm the distance from the heating tape.</li>
	<li>Spot weld nickel tabs (0.1 mm in thickness, 5 mm in width, and 100 mm in length) to the positive and negative terminals of the cell for the cell voltage measurement. Ensure that the nickel tabs are oriented in different directions to prevent them from touching each other, resulting in an external short circuit (Figure 3B).</li>
	<li>Load the cell on the cell holder, as shown in Figure 3C.</li>
	<li>Confirm that all wires of the voltage measurement and the thermocouples are routed toward the negative terminal of the cell to avoid the vent ports on the positive terminal of the cell.</li>
</ol>
3. Test chamber setup
<ol>
	<li>Turn on the light emitting diode (LED) light in the chamber.</li>
	<li>Place the cell and the cell holder on the mass balance in the chamber (see Figure 4). Connect the thermocouple connectors, heating tape, and nickel tabs to chamber-feedthrough plugs and wires.</li>
	<li>Turn on the mass balance. Tare the balance.</li>
	<li>Turn on the power supply for the hydrogen sensor.</li>
	<li>Turn on the PID controller for the heating tape. Set up the heating profile (temperature: 200 &#176;C; ramp time: 17 min). Connect the cables for the PID controller, data acquisition, and the mass balance to a laptop and start the data acquisition program on the laptop.</li>
	<li>Make sure all the sensor readings shown in the data acquisition program are reasonable: cell voltage close to the value measured in step 2.2, voltage and current input to the heating tape close to zero (since the power is not on yet), thermocouple readings close to room temperature (~25 &#176;C), chamber pressure ~1 atm, and mass reading ~0 g. After checking the measurements, turn off the data acquisition program.</li>
	<li>Adjust the front- and side-view camcorder settings: manual white balance (calibrated initially using a white paper), manual focus (fixed on the cell surface near the positive terminal), auto exposure, auto IRIS, and auto shutter speed. Make sure that the camcorder battery is full.</li>
	<li>Position the front-view camcorder on a tripod outside of the chamber (see Figure 4). Start recording on the side-view camcorder and place it inside a protection box in the chamber. Check the side-view camcorder angle and view. Lock the protection box.</li>
	<li>Double-check if there are any hazardous or unnecessary items inside the chamber and if any steps listed above have been skipped.</li>
	<li>Close the chamber and ensure all the screws on the cover plates are tightly fastened (e.g., using an impact wrench).</li>
	<li>Use the vacuum or diaphragm pump to conduct a leak check. Double-check that all the valves, cover plates, and observation windows are securely fastened. 
	NOTE: If the pressure decreases slowly or does not drop, there are leakages somewhere.</li>
	<li>Change the FTIR intake from ambient air to the chamber.</li>
	<li>Connect the FTIR return line to the chamber (see Figure 2).</li>
</ol>
4. Thermal runaway and fire experiment
<ol>
	<li>Set the PID controller to ramp-soak mode.</li>
	<li>Turn off the light in the room and the LED light in the chamber.</li>
	<li>Start the front-view camcorder recording. Use the camera to record the actions in steps 4.4 and 4.5 for time synchronization of all the collected data (sensor data, FTIR readings, and videos) after the experiments.</li>
	<li>Start the data recording in the data acquisition program on the laptop.</li>
	<li>Start the PID ramp-soak mode at 10 s on the data acquisition program timer. Turn on the chamber LED light. Start the FTIR recording.</li>
	<li>Position the front-view camcorder on the tripod and continue recording the experiment.</li>
	<li>Move to a different room and continue monitoring the data acquisition panel on the laptop through a remote-controlled desktop program. Note that this step is taken for extra precaution and is not required. Since the experiments are fully confined in the environmental chamber, the risk to the surrounding personnel is minimal.</li>
	<li>If present in the same room as the chamber, wear appropriate personal protective equipment (PPE) during the entire test period (e.g., gloves, P100 respirator, safety goggles, and fire-resistant lab coat).</li>
</ol>
5. Termination of the experiment
<ol>
	<li>When thermal runaway occurs (i.e., thermocouple readings show sudden spikes) or after the PID controller has maintained the cell temperature at 200 &#176;C for 60 min (whichever occurs first), turn off the power to the heating tape and set the PID controller to standby mode.</li>
	<li>Wait for all the thermocouple readings to drop to room temperature (&#60;50 &#176;C). Note that the cooling process for a single cell can take about 30 min.</li>
	<li>Stop the data acquisition program on the laptop, FTIR measurement, and video recording.</li>
</ol>
6. Turning off the FTIR gas analyzer
<ol>
	<li>Follow the FTIR turn-off procedure documented in the manufacturer manual, &#34;FTIR and PAS Pro for the FTT Smoke Density Chamber Standard Operating Procedure&#34;, Version 3.1.</li>
	<li>Purge the FTIR gas analyzer with nitrogen to clean the tube and analyzer for ~15 min. Ensure that the flow rate of N2 to the FTIR gas analyzer is 150-250 cc/min.</li>
	<li>While purging the gas analyzer, transfer the FTIR results to a USB memory stick.</li>
	<li>After purging, turn off the gas analyzer.</li>
	<li>Wear appropriate PPE, including a pair of heat-insulating gloves, and remove the filter in the heated filter/valve unit. Be extremely careful, as the filter/valve unit can be very hot.</li>
	<li>Clean the removed filter with an ultrasonic bath of a cleaning solution.</li>
</ol>
7. Chamber clean-up and data collection
<ol>
	<li>Before the chamber-cleanup vacuuming procedure, check if the FTIR sampling (intake) line (which is connected to the chamber) is closed or open to the ambient air. For the gas analyzer model presented in this study, select Ambient Air on the PAS Pro software or shut down the FTIR entirely. Failure to do this causes damage to the FTIR.</li>
	<li>Make sure a carbon filter is installed between the chemical-resistant diaphragm pump (Pump 1 in Figure 2) and the chamber. Mark the number of uses on the filter and replace it with a new one every ~10-15 tests.</li>
	<li>Open Valve 1 to prepare for partially vacuuming the chamber using the chemical-resistant diaphragm pump.</li>
	<li>Run the diaphragm pump until the chamber pressure drops to P1 = 9.7 psia (i.e., -5 gauge pressure).</li>
	<li>Turn off the diaphragm pump and close Valve 1.</li>
	<li>Open Valve 3 (see Figure 4) to fill the chamber with ambient air.</li>
	<li>Close Valve 3 when the chamber pressure recovers to the ambient pressure, P&#8734;.</li>
	<li>Repeat the partial vacuuming procedure (steps 7.3-7.7) five times. Through this, the exhaust gas percentage in the chamber should drop to (P1/P&#8734;)5 = 12.5%.</li>
	<li>Open Valve 2 to prepare for fully vacuuming the chamber using the vacuum pump (Pump 2 in Figure 2).</li>
	<li>Run the vacuum pump until the chamber pressure drops to P2 = 4.7 psia (or -10 psia gauge pressure).</li>
	<li>Turn off the pump and close Valve 2.</li>
	<li>Open Valve 3 to fill the chamber with ambient air until the chamber pressure recovers to the ambient pressure, P&#8734;.</li>
	<li>Repeat the complete vacuuming procedure (steps 7.9-7.12) two times. 
	NOTE: After the partial and complete vacuuming procedures, the exhaust gas percentage in the chamber should be lower than 1.3%.</li>
	<li>Open the chamber and retrieve the camcorder and the cell.</li>
	<li>Turn off the mass balance.</li>
	<li>Use a wet paper towel to clean the interior of the chamber (e.g., remove all debris and wipe the inner walls of the chamber).</li>
	<li>Take photos before, during, and after taking the cell off the cell holder.</li>
	<li>Weigh the cell and record the post-test mass of the cell.</li>
	<li>Retrieve all the recorded data (thermocouple readings, cell voltage, heating tape voltage, current, chamber pressure, and cell mass measurement) from the laptop and the video recordings from the two camcorders.</li>
	<li>Combine the collected videos using a video editing software. Record the onset time of the major events, such as cell venting, thermal runaway, and fire. Save the combined video in a desired format (e.g., mp4 or avi).</li>
	<li>Post-process the collected data and generate plots to visualize the time evolution of all measurements.</li>
</ol>

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The authors have no conflicts of interest to disclose.

The most critical steps in the protocol are those concerning the toxic gases released in the LIB thermal runaway. The leak test in step 3.11 needs to be carefully performed to ensure that the toxic gases are confined in the chamber during the experiments. The chamber gas clean-up procedures (steps 7.1-7.14) must also be properly done to mitigate the hazard from the toxic gases. Toxic gases may constitute only a small fraction of the vent gas during LIB thermal runaway. However, even very low concentrations of some toxic ...

In the last few decades, lithium-ion batteries (LIBs) have gained popularity and benefited from tremendous technological advancements. Owing to various advantages (e.g., high energy density, low maintenance, low self-discharge and charge times, and long lifespan), the LIB has been considered a promising energy storage technology and extensively used in various applications, such as large energy storage systems (ESSs), electric vehicles (EVs), and portable electronic devices. While the global demand for LIB cells is expected to double from 725 GWh in 2020 to 1,500 GWh in 20301, there has been a substantial increase in fires and explosions related to LIBs in recent years2. These accidents demonstrate the high risks associated with LIBs, raising concerns regarding their large-scale utilization. To mitigate these concerns, it is crucial to gain a thorough understanding of the process of LIB thermal runaway leading to fires.
Previous accidents have revealed that LIB cells fail when the cell electrochemistry is disrupted by overheating in abnormal operating circumstances (such as external short circuit, rapid discharge, overcharging, and physical damage) or due to manufacturing defects and poor design2,3,4. These events lead to the decomposition of the solid-electrolyte interface (SEI), stimulating highly exothermic chemical reactions between electrode materials and electrolytes. When the heat produced in these reactions exceeds that being dissipated, it results in rapid self-heating of the cells, also known as thermal runaway. Internal temperature and pressure can continue rising until built-up pressure causes the battery to rupture and release flammable, toxic gases at high speed. In a multi-cell battery configuration, a thermal runaway in a single cell, if not controlled, can lead to thermal runaway propagation to other cells and incidents of fire and explosion at catastrophic levels, especially in enclosed spaces with limited ventilation. This poses significant threats to human safety and structures.
In the past few decades, a number of studies have been carried out to investigate the thermal runaway reactions of LIBs leading to the combustion of organic electrolytes inside the battery and the release of flammable gases under different heating conditions2,5,6,7,8,9,10,11,12. For example, Jhu et al.10 demonstrated the hazardous nature of charged cylindrical LIBs compared to uncharged ones using an adiabatic calorimeter. Many other studies focused on the thermal runaway behavior of LIBs at different state-of-charges (SOCs). For example, Joshi et al.13 investigated the thermal runaway of various types of commercial LIBs (cylindrical and pouch) at different SOCs. It was noticed that cells at higher SOCs had a higher chance of undergoing thermal runaway compared to those at lower SOCs. In addition, the minimum SOC for a thermal runaway to occur varied with the cell formats and chemistries. Roth et al.11 tested cylindrical LIBs in an accelerating rate calorimeter (ARC) and observed that, as the SOC increased, the onset temperature of thermal runaway decreased and the acceleration rate increased. Golubkov et al.12 developed a custom-designed test stand and showed that the maximum surface temperature of cylindrical LIBs could be as high as 850 &#176;C. Ribi&#232;re et al.14 used a fire propagation apparatus to investigate the fire-induced hazards of pouch LIBs and noticed that the heat release rate (HRR) and toxic gas production varied significantly with the cell SOC. Chen et al.15 studied the fire behaviors of two different 18650 LIBs (LiCoO2 and LiFePO4) at different SOCs, using a custom-made in situ calorimeter. HRR, mass loss, and maximum surface temperature were found to increase with SOC. It was also demonstrated that the risk of explosion was higher for a fully charged lithium cobalt oxide (LiCoO2) cathode 18650 cell compared to a lithium iron phosphate (LiFePO2) cathode 18650 cell. Fu et al.16 and Quang et al.17 conducted fire experiments on LIBs (at 0%-100% SOCs) using a cone calorimeter. It was observed that LIBs at a higher SOC resulted in higher fire hazards due to shorter lengths of time to ignition and explosion, higher HRR, higher surface temperature, and higher CO and CO2 emissions.
To summarize, previous studies using different calorimeters18,19&#160;(ARC, adiabatic calorimetry, C80 calorimetry, and modified bomb calorimetry) have provided abundant data on the electrochemical and thermal processes associated with LIB thermal runaway and fires (e.g., HRR, compositions of the vented gases) and their dependencies on the SOC, battery chemistry, and incident heat flux2,3,7,20. However, most of these methods were designed originally for conventional solid combustibles (e.g., cellulose samples, plastic) and provide limited information when applied to LIB fires. While some previous tests measured the HRR and the total energy generated from chemical reactions, the kinetics aspects of post-thermal runaway fires were not fully addressed.
The severity of hazards during thermal runaway is mainly dependent on the nature and composition of the gases released2,5. Therefore, it is important to characterize the released gases, the venting rate, and their dependence on the SOC. Some previous studies measured the vent gas compositions of LIB thermal runaway in an inert environment (e.g., in nitrogen or argon)12,21,22; the fire component during the thermal runaway was excluded. In addition, these measurements were mostly performed post-experiments (instead of in situ). Evolutions of vent gas composition during and post-thermal runaway, especially those involving fires and toxic gases, remained under-explored.
It is known that thermal runaway disrupts the electrochemistry of the battery and impacts the cell voltage and temperature. A comprehensive test to characterize the thermal runaway process of the LIB should, therefore, provide simultaneous measurement of the temperature, mass, voltage, and vented gases (rate and composition). This has not been achieved in a single setup in the previous studies. In this study, a new apparatus and test protocol are developed to collect time-resolved data on the cell information, gas compositions, and fire characteristics during and post-thermal runaway of LIB cells23. The test apparatus is shown in Figure 1A. A large (~600 L) environmental chamber is used to confine the thermal runaway event. The chamber is equipped with a pressure relief valve (with a set gauge pressure at 0.5 psig) to prevent pressure rise in the chamber. A Fourier transform infrared (FTIR) gas analyzer is connected to the chamber for in situ gas sampling throughout the test. It detects 21 gas species (H2O, CO2, CO, NO, NO2, N2O, SO2, HCl, HCN, HBr, HF, NH3, C2H4, C2H6, C3H8, C6H14, CH4, HCHO, C6H6O, C3H4O, and COF2). The FTIR sampling rate is 0.25 Hz. In addition, a standalone hydrogen sensor is installed inside the chamber near the FTIR sampling port to record the H2 concentration. Two pumps (a 1.3 cfm chemical-resistant diaphragm pump and a 0.5 hp vacuum pump) are installed in the chamber exhaust line. After each experiment, a chamber clean-up procedure is followed to filter and pump the chamber gas directly to the building exhaust line.
In each experiment, the cell is set up inside the chamber in a sample holder (Figure 1B). Thermal runaway is triggered by a proportional-integral-derivative (PID)-controlled electric heating tape at a constant heating rate of 10 &#176;C/min. Cell surface temperatures are recorded by thermocouples in three different locations along the length of the cell. The mass loss of the cell is measured by a mass balance. The chamber pressure is monitored by a pressure transducer. The cell voltage and the power input (voltage and current) to the heating tape are also recorded. All sensor readings (thermocouples, mass loss, cell voltage, heating tape current, and voltage) are collected by a custom data acquisition program at a rate of 2 Hz. Lastly, two camcorders (1920 pixel x 1080 pixel resolution) are used to record the entire process of the experiments from two different angles.
The objective of developing this new test method is twofold: 1) to characterize the smoke and fire behaviors associated with LIB thermal runaway and 2) to provide time-resolved experimental data that enables the development of high-validity numerical models for battery fires. The long-term goal is to advance the understanding of how thermal runaway propagates between cells in a battery pack and how a battery fire scales up when going from single cells to multi-cell batteries. Ultimately, this will help improve guidelines and protocols for storing and transporting LIBs safely.

<table><tbody><tr><td>Balance</td><td>A&amp;amp;D</td><td>EJ-6100</td><td></td></tr><tr><td>Carbon filter</td><td>Whatman</td><td>WHA67041500</td><td></td></tr><tr><td>Current transducer</td><td>NK Technologies</td><td>AT1-010-000-FT</td><td></td></tr><tr><td>Front camera</td><td>Sony</td><td>FDR-AX53</td><td></td></tr><tr><td>FTIR gas analyzer</td><td>Fire Testing Technology</td><td>Protea atmosFIR AFS-A-15</td><td></td></tr><tr><td>Heating tape (1.00&quot; x 2.00&quot;)</td><td>Birk Manufacturing, Inc.</td><td>BK3512-19.6-L24-03</td><td></td></tr><tr><td>High-temperature resistant tape</td><td>Kapton</td><td></td><td></td></tr><tr><td>Hydrogen sensor</td><td>Amphenol</td><td>AX220135</td><td></td></tr><tr><td>K-type, thermocouple</td><td>Omega</td><td>KMQSS-020U-12</td><td></td></tr><tr><td>LabVIEW</td><td>National Instruments</td><td></td><td></td></tr><tr><td>Matlab</td><td>MathWorks</td><td></td><td></td></tr><tr><td>NI-9213</td><td>National Instruments</td><td>NI-9213</td><td></td></tr><tr><td>NI-9219</td><td>National Instruments</td><td>NI-9219</td><td></td></tr><tr><td>NI-cDAQ-9174</td><td>National Instruments</td><td>NI-cDAQ-9174</td><td></td></tr><tr><td>NI-USB-6009</td><td>National Instruments</td><td>NI-USB-6009</td><td></td></tr><tr><td>PID controller</td><td>Omega</td><td>CN8200</td><td></td></tr><tr><td>PILOT5000 Chemical Resistant Diaphragm Vacuum Pump</td><td>The Lab Depot</td><td>TLD5000</td><td></td></tr><tr><td>Pressure relief valve</td><td>Straval</td><td>RVL20-10T-N4675</td><td></td></tr><tr><td>Pressure Transmitter</td><td>Keller</td><td>0308.01601.081303.02</td><td></td></tr><tr><td>Pure Nickel Strip (0.1x5x100mm 99.6% Nickel)</td><td>U.S. Solid Product</td><td></td><td></td></tr><tr><td>Respirator</td><td>McMaster</td><td>55865T52</td><td></td></tr><tr><td>Respirator Cartridge</td><td>Honeywell&amp;nbsp;</td><td>75Scp100L</td><td></td></tr><tr><td>Rotary vane vacuum pump (0.5 hp)</td><td>Alcatel</td><td>Pascal 2010</td><td></td></tr><tr><td>Side camera</td><td>Sony</td><td>HDR-CX110</td><td></td></tr><tr><td>Spot Welder</td><td>SUNKKO</td><td>737G+</td><td></td></tr><tr><td>TeamViewer</td><td>TeamViewer</td><td></td><td></td></tr><tr><td>Voltage transducer</td><td>CR Magnetics Inc.</td><td>CR4510-50</td><td></td></tr></tbody></table>

in situ gas analysis and fire characterization of lithium-ion cells during thermal runaway using an environmental chamber

An experimental apparatus and a standard operating procedure (SOP) are developed to collect time-resolved data on the gas compositions and fire characteristics during and post-thermal runaway of lithium-ion battery (LIB) cells. A 18650 cylindrical cell is conditioned to a desired state-of-charge (SOC; 30%, 50%, 75%, and 100%) before each experiment. The conditioned cell is forced into a thermal runaway by an electrical heating tape at a constant heating rate (10 &#176;C/min) in an environmental chamber (volume: ~600 L). The chamber is connected to a Fourier transform infrared (FTIR) gas analyzer for real-time concentration measurements. Two camcorders are used to record major events, such as cell venting, thermal runaway, and the subsequent burning process. The conditions of the cell, such as surface temperature, mass loss, and voltage, are also recorded. With the data obtained, cell pseudo-properties, venting gas compositions, and venting mass rate can be deduced as functions of cell temperature and cell SOC. While the test procedure is developed for a single cylindrical cell, it can be readily extended to test different cell formats and study fire propagation between multiple cells. The collected experimental data can also be used for the development of numerical models for LIB fires.

Videos representing typical thermal runaway processes with and without fires are included in Supplementary File 1 and Supplementary File 2, respectively. Key events are depicted in Figure 5. As the cell temperature is raised (to ~110-130 &#176;C), the cell starts swelling, indicating the buildup of the internal pressure (caused by the vaporization of electrolytes and the thermal expansion of gases inside the cell2). This is followed b...

Watch this Scientific Journal Video about In Situ Gas Analysis and Fire Characterization of Lithium-Ion Cells During Thermal Runaway Using an Environmental Chamber at JoVE.com

In Situ Gas Analysis and Fire Characterization of Lithium-Ion Cells During Thermal Runaway Using an Environmental Chamber

Here, we describe a test procedure developed to characterize thermal runaway and fires in lithium-ion cells through in situ measurements of various parameters in an environmental chamber.

In Situ Gas Analysis and Fire Characterization of Lithium-Ion Cells During Thermal Runaway Using an Environmental Chamber

An experimental apparatus and a standard operating procedure (SOP) are developed to collect time-resolved data on the gas compositions and fire ...

in-situ-gas-analysis-fire-characterization-lithium-ion-cells-during

Research

JoVE Journal

Engineering

2.0K Views.  Case Western Reserve University. Thermische runaway in lithium-ionbatterijen treedt op als gevolg van verschillende oorzaken, wat ook kan resulteren in zeer verschillende worst case uitkomsten. In deze methode proberen we een catastrofaal gevaar in een enkele cel te simuleren, en het protocol heeft aangetoond dat het consistentie in resultaten biedt voor de simulatie van het type gevaar dat we willen creëren. Het grote voordeel van deze testprocedure is dat deze verschillende parameters in situ meet in één enkele test.

Video: In Situ Gas Analysis and Fire Characterization of Lithium-Ion Cells During Thermal Runaway Using an Environmental Chamber

Construction and Testing of Coin Cells of Lithium Ion Batteries

Rechargeable lithium ion batteries have wide applications in electronics, where customers always demand more capacity and longer lifetime. Lithium ion batteries have also been considered to be used in electric and hybrid vehicles1 or even electrical grid stabilization systems2. All these applications simulate a dramatic increase in the research and development of battery materials3-7, including new materials3,8, doping9, nanostructuring10-13, coatings or surface modifications14-17 and novel binders18. Consequently, an increasing number of physicists, chemists and materials scientists have recently ventured into this area. Coin cells are widely used in research laboratories to test new battery materials; even for the research and development that target large-scale and high-power applications, small coin cells are often used to test the capacities and rate capabilities of new materials in the initial stage. 
 In 2010, we started a National Science Foundation (NSF) sponsored research project to investigate the surface adsorption and disordering in battery materials (grant no. DMR-1006515). In the initial stage of this project, we have struggled to learn the techniques of assembling and testing coin cells, which cannot be achieved without numerous help of other researchers in other universities (through frequent calls, email exchanges and two site visits). Thus, we feel that it is beneficial to document, by both text and video, a protocol of assembling and testing a coin cell, which will help other new researchers in this field. This effort represents the "Broader Impact" activities of our NSF project, and it will also help to educate and inspire students.
In this video article, we document a protocol to assemble a CR2032 coin cell with a LiCoO2 working electrode, a Li counter electrode, and (the mostly commonly used) polyvinylidene fluoride (PVDF) binder. To ensure new learners to readily repeat the protocol, we keep the protocol as specific and explicit as we can. However, it is important to note that in specific research and development work, many parameters adopted here can be varied. First, one can make coin cells of different sizes and test the working electrode against a counter electrode other than Li. Second, the amounts of C black and binder added into the working electrodes are often varied to suit the particular purpose of research; for example, large amounts of C black or even inert powder were added to the working electrode to test the "intrinsic" performance of cathode materials14. Third, better binders (other than PVDF) have also developed and used18. Finally, other types of electrolytes (instead of LiPF6) can also be used; in fact, certain high-voltage electrode materials will require the uses of special electrolytes7.

A protocol to construct and test coin cells of lithium ion batteries is described. The specific procedures of making a working electrode, preparing a counter electrode, assembling a cell inside a glovebox and testing the cell are presented.

Rechargeable lithium ion batteries have wide applications in electronics, where customers always demand more capacity and longer lifetime.  Lithium ion ...

Characterization of Electrode Materials for Lithium Ion and Sodium Ion Batteries Using Synchrotron Radiation Techniques

Intercalation compounds such as transition metal oxides or phosphates are the most commonly used electrode materials in Li-ion and Na-ion batteries. During insertion or removal of alkali metal ions, the redox states of transition metals in the compounds change and structural transformations such as phase transitions and/or lattice parameter increases or decreases occur. These behaviors in turn determine important characteristics of the batteries such as the potential profiles, rate capabilities, and cycle lives. The extremely bright and tunable x-rays produced by synchrotron radiation allow rapid acquisition of high-resolution data that provide information about these processes. Transformations in the bulk materials, such as phase transitions, can be directly observed using X-ray diffraction (XRD), while X-ray absorption spectroscopy (XAS) gives information about the local electronic and geometric structures (e.g.&#160;changes in redox states and bond lengths). In situ experiments carried out on operating cells are particularly useful because they allow direct correlation between the electrochemical and structural properties of the materials. These experiments are time-consuming and can be challenging to design due to the reactivity and air-sensitivity of the alkali metal anodes used in the half-cell configurations, and/or the possibility of signal interference from other cell components and hardware. For these reasons, it is appropriate to carry out ex situ experiments (e.g.&#160;on electrodes harvested from partially charged or cycled cells) in some cases. Here, we present detailed protocols for the preparation of both ex situ and in situ samples for experiments involving synchrotron radiation and demonstrate how these experiments are done.

We describe the use of synchrotron X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) techniques to probe details of intercalation/deintercalation processes in electrode materials for Li-ion and Na-ion batteries. Both in situ and ex situ experiments are used to understand structural behavior relevant to the operation of devices

Intercalation compounds such as transition metal oxides or phosphates are the most commonly used electrode materials in Li-ion and Na-ion batteries. ...

Characterization of Thermal Transport in One-dimensional Solid Materials

The TET (transient electro-thermal) technique is an effective approach developed to measure the thermal diffusivity of solid materials, including conductive, semi-conductive or nonconductive one-dimensional structures. This technique broadens the measurement scope of materials (conductive and nonconductive) and improves the accuracy and stability. If the sample (especially biomaterials, such as human head hair, spider silk, and silkworm silk) is not conductive, it will be coated with a gold layer to make it electronically conductive. The effect of parasitic conduction and radiative losses on the thermal diffusivity can be subtracted during data processing. Then the real thermal conductivity can be calculated with the given value of volume-based specific heat (&#961;cp), which can be obtained from calibration, noncontact photo-thermal technique or measuring the density and specific heat separately. In this work, human head hair samples are used to show how to set up the experiment, process the experimental data, and subtract the effect of parasitic conduction and radiative losses.

The TET (transient electro-thermal) technique is an effective approach developed to measure the thermal diffusivity of solid materials.

The TET (transient electro-thermal) technique is an effective approach developed to measure the thermal diffusivity of solid materials, including ...

In Situ Neutron Powder Diffraction Using Custom-made Lithium-ion Batteries

Li-ion batteries are widely used in portable electronic devices and are considered as promising candidates for higher-energy applications such as electric vehicles.1,2 However, many challenges, such as energy density and battery lifetimes, need to be overcome before this particular battery technology can be widely implemented in such applications.3 This research is challenging, and we outline a method to address these challenges using in situ NPD to probe the crystal structure of electrodes undergoing electrochemical cycling (charge/discharge) in a battery. NPD data help determine the underlying structural mechanism responsible for a range of electrode properties, and this information can direct the development of better electrodes and batteries.
We briefly review six types of battery designs custom-made for NPD experiments and detail the method to construct the &#8216;roll-over&#8217; cell that we have successfully used on the high-intensity NPD instrument, WOMBAT, at the Australian Nuclear Science and Technology Organisation (ANSTO). The design considerations and materials used for cell construction are discussed in conjunction with aspects of the actual in situ NPD experiment and initial directions are presented on how to analyze such complex in situ data.

In Situ Neutron Powder Diffraction Using Custom-made Lithium-ion Batteries

We describe the design and construction of an electrochemical cell for the examination of electrode materials using in situ neutron powder diffraction (NPD). We briefly comment on alternate in situ NPD cell designs and discuss methods for the analysis of the corresponding in situ NPD data produced using this cell.

Li-ion batteries are widely used in portable electronic devices and are considered as promising candidates for higher-energy applications such as electric ...

Non-aqueous Electrode Processing and Construction of Lithium-ion Coin Cells

Research into new and improved materials to be utilized in lithium-ion batteries (LIB) necessitates an experimental counterpart to any computational analysis. Testing of lithium-ion batteries in an academic setting has taken on several forms, but at the most basic level lies the coin cell construction. In traditional LIB electrode preparation, a multi-phase slurry composed of active material, binder, and conductive additive is cast out onto a substrate. An electrode disc can then be punched from the dried sheet and used in the construction of a coin cell for electrochemical evaluation. Utilization of the potential of the active material in a battery is critically dependent on the microstructure of the electrode, as an appropriate distribution of the primary components are crucial to ensuring optimal electrical conductivity, porosity, and tortuosity, such that electrochemical and transport interaction is optimized. Processing steps ranging from the combination of dry powder, wet mixing, and drying can all critically affect multi-phase interactions that influence the microstructure formation. Electrochemical probing necessitates the construction of electrodes and coin cells with the utmost care and precision. This paper aims at providing a step-by-step guide of non-aqueous electrode processing and coin cell construction for lithium-ion batteries within an academic setting and with emphasis on deciphering the influence of drying and calendaring.

Non-aqueous electrode processing is central to the construction of coin cells and the evaluation of new electrode chemistries for lithium-ion batteries. A step-by-step guide to the basic practices needed as an electrochemical engineer working with batteries in an academic experimental setting is furnished.

Research into new and improved materials to be utilized in lithium-ion batteries (LIB) necessitates an experimental counterpart to any computational ...

Printing Fabrication of Bulk Heterojunction Solar Cells and In Situ Morphology Characterization

Polymer-based materials hold promise as low-cost, flexible efficient photovoltaic devices. Most laboratory efforts to achieve high performance devices have used devices prepared by spin coating, a process that is not amenable to large-scale fabrication. This mismatch in device fabrication makes it difficult to translate quantitative results obtained in the laboratory to the commercial level, making optimization difficult. Using a mini-slot die coater, this mismatch can be resolved by translating the commercial process to the laboratory and characterizing the structure formation in the active layer of the device in real time and in situ as films are coated onto a substrate. The evolution of the morphology was characterized under different conditions, allowing us to propose a mechanism by which the structures form and grow. This mini-slot die coater offers a simple, convenient, material efficient route by which the morphology in the active layer can be optimized under industrially relevant conditions. The goal of this protocol is to show experimental details of how a solar cell device is fabricated using a mini-slot die coater and technical details of running in situ structure characterization using the mini-slot die coater.

Printing Fabrication of Bulk Heterojunction Solar Cells and In Situ Morphology Characterization

Here, we present a protocol to fabricate organic thin film solar cells using a mini-slot die coater and related in-line structure characterizations using synchrotron scattering techniques.

Polymer-based materials hold promise as low-cost, flexible efficient photovoltaic devices. Most laboratory efforts to achieve high performance devices ...

Experimental Methodology for Estimation of Local Heat Fluxes and Burning Rates in Steady Laminar Boundary Layer Diffusion Flames

Modeling the realistic burning behavior of condensed-phase fuels has remained out of reach, in part because of an inability to resolve the complex interactions occurring at the interface between gas-phase flames and condensed-phase fuels. The current research provides a technique to explore the dynamic relationship between a combustible condensed fuel surface and gas-phase flames in laminar boundary layers. Experiments have previously been conducted in both forced and free convective environments over both solid and liquid fuels. A unique methodology, based on the Reynolds Analogy, was used to estimate local mass burning rates and flame heat fluxes for these laminar boundary layer diffusion flames utilizing local temperature gradients at the fuel surface. Local mass burning rates and convective and radiative heat feedback from the flames were measured in both the pyrolysis and plume regions by using temperature gradients mapped near the wall by a two-axis traverse system. These experiments are time-consuming and can be challenging to design as the condensed fuel surface burns steadily for only a limited period of time following ignition. The temperature profiles near the fuel surface need to be mapped during steady burning of a condensed fuel surface at a very high spatial resolution in order to capture reasonable estimates of local temperature gradients. Careful corrections for radiative heat losses from the thermocouples are also essential for accurate measurements. For these reasons, the whole experimental setup needs to be automated with a computer-controlled traverse mechanism, eliminating most errors due to positioning of a micro-thermocouple. An outline of steps to reproducibly capture near-wall temperature gradients and use them to assess local burning rates and heat fluxes is provided.

We describe the use of micro-thermocouples to estimate local temperature gradients in steady laminar boundary layer diffusion flames. By extension of the Reynolds Analogy, local temperature gradients can be further used to estimate the local mass burning rates and heat fluxes in such flames with high accuracy.

Modeling the realistic burning behavior of condensed-phase fuels has remained out of reach, in part because of an inability to resolve the complex ...

Focused Ion Beam Fabrication of LiPON-based Solid-state Lithium-ion Nanobatteries for In Situ Testing

Solid-state electrolytes are a promising replacement for current organic liquid electrolytes, enabling higher energy densities and improved safety of lithium-ion (Li-ion) batteries. However, a number of setbacks prevent their integration into commercial devices. The main limiting factor is due to nanoscale phenomena occurring at the electrode/electrolyte interfaces, ultimately leading to degradation of battery operation. These key problems are highly challenging to observe and characterize as these batteries contain multiple buried interfaces. One approach for direct observation of interfacial phenomena in thin film batteries is through the fabrication of electrochemically active nanobatteries by a focused ion beam (FIB). As such, a reliable technique to fabricate nanobatteries was developed and demonstrated in recent work. Herein, a detailed protocol with a step-by-step process is presented to enable the reproduction of this nanobattery fabrication process. In particular, this technique was applied to a thin film battery consisting of LiCoO2/LiPON/a-Si, and has further been previously demonstrated by in situ cycling within a transmission electron microscope.

Focused Ion Beam Fabrication of LiPON-based Solid-state Lithium-ion Nanobatteries for In Situ Testing

A protocol for the fabrication of electrochemically active LiPON-based solid-state lithium-ion nanobatteries using a focused ion beam is presented.

Solid-state electrolytes are a promising replacement for current organic liquid electrolytes, enabling higher energy densities and improved safety of ...

Accelerating Rate Calorimetry and Complementary Techniques to Characterize Battery Safety Hazards

The hazards associated with lithium-based battery chemistries are well-documented due to their catastrophic nature. Risk is typically qualitatively assessed through an engineering risk matrix. Within the matrix, potentially hazardous events are categorized and ranked in terms of severity and probability to provide situational awareness to decision makers and stakeholders. The stochastic nature of battery failures, particularly the lithium-ion chemistry, makes the probability axis of a matrix difficult to properly assess. Fortunately, characterization tools exist, such as accelerated rate calorimetry (ARC), that characterize degrees of battery failure severity. ARC has been used extensively to characterize reactive chemicals but can provide a new application to induce battery failures under safe, controlled experimental conditions and quantify critical safety parameters. Due to the robust nature of the extended volume calorimeter, cells may be safely taken to failure due to a variety of abuses: thermal (simple heating of cell), electrochemical (overcharge), electrical (external short circuit), or physical (crush or nail penetration). This article describes the procedures to prepare and instrument a commercial lithium-ion battery cell for failure in an ARC to collect valuable safety data: onset of thermal runaway, endotherm associated with polymer separator melting, pressure release during thermal runaway, gaseous collection for analytical characterization, maximum temperature of complete reaction, and visual observation of decomposition processes using a high temperature borescope (venting and cell can breach). A thermal &#8220;heat-wait-seek&#8221; method is used to induce cell failure, in which the battery is heated incrementally to a set point, then the instrument identifies heat generation from the battery. As heat generates a temperature rise in the battery, the calorimeter temperature follows this temperature rise, maintaining an adiabatic condition. Therefore, the cell does not exchange heat with the external environment, so all heat generation from the battery under failure is captured.

A method to characterize the potential failure hazards of lithium batteries is achieved with accelerating rate calorimetry. Heat and pressure release, visual observation of the failure event, and the capture of evolved gases are collected in this experiment to identify the worst credible threats of batteries taken to failure.

The hazards associated with lithium-based battery chemistries are well-documented due to their catastrophic nature. Risk is typically qualitatively ...

Chemistry

Identification and Quantification of Decomposition Mechanisms in Lithium-Ion Batteries; Input to Heat Flow Simulation for Modeling Thermal Runaway

The risks and possible accidents related to the normal use of lithium-ion batteries remain a serious concern. In order to get a better understanding of thermal runaway (TR), the exothermic decomposition reactions in anode and cathode were studied, using a Simultaneous Thermal Analysis (STA)/Gas Chromatography-Mass Spectrometry (GC-MS)/Fourier Transform Infrared (FTIR) spectrometer system. These techniques allowed the identification of the reaction mechanisms in each electrode, owing to the analysis of evolved gaseous species, the amount of heat released and mass loss. These results provided insight into the thermal events happening within a broader temperature range than covered in previously published models. This allowed the formulation of an improved thermal model to depict TR. The heat of reaction, activation energy, and frequency factor (thermal triplets) for each major exothermic process at material level were investigated in a Lithium Nickel-Manganese-Cobalt-Oxide (NMC (111))-Graphite battery cell. The results were analyzed, and their kinetics were derived. These data can be used to successfully simulate the experimental heat flow.

This work aims at determining the reaction kinetics of Li-ion battery cathode and anode materials undergoing thermal runaway (TR). Simultaneous Thermal Analysis (STA)/Fourier Transform Infrared (FTIR) spectrometer/Gas Chromatography Mass Spectrometry (GC-MS) were used to reveal thermal events and to detect evolved gases.

The risks and possible accidents related to the normal use of lithium-ion batteries remain a serious concern. In order to get a better understanding of ...

In Situ Gas Analysis and Fire Characterization of Lithium-Ion Cells During Thermal Runaway Using an Environmental Chamber

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