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

Summary

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.

Abstract

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 °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.

Introduction

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 relate....

Protocol

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.

1. 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).
2. 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 pre....

Results

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 °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 by the.......

Discussion

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 .......

Materials

List of materials used in this article

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