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Size distribution and elemental composition of vent particles from abused prismatic Ni-rich automotive lithium-ion batteries
Journal of Energy Storage 26 (2019) 100991
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Size distribution and elemental composition of vent particles from abused prismatic Ni-rich automotive lithium-ion batteries
T
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Yajun Zhang, Hewu Wang, Weifeng Li , Cheng Li, Minggao Ouyang State Key Laboratory of Automotive Safety and Energy, Tsinghua University, Beijing 100084, PR China
A R T I C LE I N FO
A B S T R A C T
Keywords: Lithium-ion batteries Settleable PM Particle size distribution Element
The lithium-ion battery (LIB) jet is often accompanied by particulate matter (PM) (e.g. spark) during vent and combustion caused by thermal runaway. These hot PM could ignite the combustible vent gases, and the settleable matter may promote water and soil pollution. The aim of this study is to reveal the statistical size distribution and elemental composition of the settleable PM released by LIBs after thermal runaway. A fully charged commercial 50 Ah Li(Ni0.6Mn0.2Co0.2)O2 cell was triggered by heating in a sealed chamber. These PM were divided into 4 samples using sieves. The sizes were analyzed and the elements were detected. The results show that these PM account for 11.20% of the cell mass. Nearly 45% of particles by mass were found to have a size less than 0.85 mm, with the median size being approximately 198 um. The main elements are carbon, nickel, cobalt, etc. The content of metallic elements is approximately 40%. The emissions also contain potentially toxic elements, including aluminum, lithium, fluorine, etc. The element species in different samples are similar, but their contents differ. The size distribution provides a basis for the design of the particle filter pore, and elemental composition reveals the pollution of LIB emissions.
1. Introduction In recent years, regulatory restrictions on emissions and environmental awareness have prompted a surge in battery electric vehicles and plug-in hybrid electric vehicles and have led to reductions in the usage of traditional internal combustion engine vehicles [1–5]. After many years of development, lithium-ion batteries (LIBs) have become increasingly acceptable as the main power source in vehicles due to their higher energy density, longer calendar or cycle life, and increased reliability [6]. The global stock of electric cars and plug-in hybrid electric vehicles surpassed the 3 million mark in 2017, accompanied by an average annual increase of 56% in 2015 and 2016 (1.2 million and 2 million, respectively) according to the International Energy Agency [7]. Safety aspects concerning these vehicles have also received increasing research attention, such as gas or smoke venting hazards related to failures of on-board large-capacity power batteries, which are difficult to firefight [8–10]. One major battery failure mode is called thermal runaway, where an increase in temperature changes conditions, driving a further increase in temperature [11,12]. The battery vent gas released by LIB in the process of thermal runaway is a key fire hazard [6]. Therefore, many researchers have studied the formation mechanisms of vent gas, as well as the effects of state of charge (SOC), battery type, and battery aging on the ⁎
components and amount of vent gas [13–27]. Vent gas primarily forms from the decomposition of negative solid-electrolyte interface film [28,29], reactions between the anodes and electrolytes [28], decomposition of cathode materials [28,30–32], decomposition of electrolytes [33], decomposition of binders [34], and reactions between various material decomposition products. Somandepalli et al. [22] studied variations in the composition, concentration, and volume of vent gas under different SOCs. They placed the battery in a sealed 6-L chamber filled with argon (Ar) and heated it until vent. The results showed that the gaseous vents mainly included carbon dioxide (CO2), carbon monoxide (CO), hydrogen (H2), and hydrocarbons with different numbers of carbon atoms such as methane (CH4), ethylene (C2H4), and ethane (C2H6). As the SOC increased, the CO2 concentration decreased, the CO and CH4 concentrations increased, the H2 concentration remained relatively unchanged, and total hydrocarbons varied between 20% and 30%. The normalized volume of gaseous vents increased with increasing SOC. In addition to electrolytes and other combustible gases, the battery jet is often accompanied by high-temperature particle matter (PM) during venting and combustion [35,36]. These high-temperature particles are often accompanied by sparks with temperatures as high as 1200 °C [37]. Once the combustible mixture and high-temperature particles have been simultaneously released into the external
Corresponding author. E-mail address: [email protected] (W. Li).
https://doi.org/10.1016/j.est.2019.100991 Received 1 August 2019; Received in revised form 11 September 2019; Accepted 28 September 2019 2352-152X/ © 2019 Elsevier Ltd. All rights reserved.
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Nomenclature AAM ACC Ar Al B Ba C Ca CAM CCC CO2 CO CH4 C2H4 C2H6 Cu Co Cr F Fe
K Li LIB Mg Mo Mn Na NMC Ni P PM S Sb Si Sn SOC Sr Ti Zr Zn V
anode active material anode current collector argon aluminum boron barium carbon calcium cathode active material cathode current collector carbon dioxide carbon monoxide methane ethylene ethane copper cobalt chromium fluorine iron
environment and exposed to oxygen, fire or even explosion could occur [37]. In addition, because high-temperature particulate has large kinetic energy, it is easily scattered and exposed to combustible materials, making it vulnerable to catching fire. Studying the particle size distribution characteristics of settleable PM ejected by LIBs can provide guidance on how to suppress sparks and decrease inflammability by reducing the fire source, as well as establish a fire safety active control strategy for LIBs. In addition, revealing the elemental composition and major components of the settleable PM can allow proper handling of the residue from a LIB fire; i.e., whether it can be directly in contact with human skin, whether it can be released into the natural environment, etc. However, although there have been studies on the phenomenon of venting high-temperature particles during the LIB thermal runaway process, it has not been studied in detail. The particle size distribution and elemental composition of the particles released by LIBs remain unclear. It should be noted that particles released by LIBs are a result of the combined action of all materials inside the battery, so the formation process needs further research, and will not be studied in this paper. Fortunately, the cathode particles’ behavior under thermal abuse conditions has been thoroughly studied and well-documented in the literature [38–40]. For example, Besli et al. [38] investigated the thermal decomposition, fracture, and oxygen evolution of chemically de-lithiated Li0.3Ni0.8Co0.15Al0.05O2 particles upon heating from 25 °C to 450 °C using a number of advanced X-ray and electron probes, and observed a continuous reduction of the Ni oxidation state upon heating, as well as the release of oxygen from the NCA lattice undergoing thermally induced phase transformations. In addition, recent advances [41,42] in the interface engineering of solid-state Li-ion batteries from a microscopic perspective provide sound research methods for researchers to study the PM released by LIBs. The purpose of this research is to reveal the size distribution and elemental composition of the settleable particulate matter released by LIBs during thermal runaway. With this in mind, a 50 Ah, 3.65 V, commercial prismatic LIB cell with lithium nickel manganate cobalt (NMC) oxide cathode was used, and it was placed in a sealed chamber and heated by a 1 kW heater at 100% SOC to trigger the thermal runaway. At the termination of the experiment, the particles scattered throughout the sealed chamber during the battery venting caused by thermal runaway were collected. The settleable PM collected were divided into four samples—a, b, c and d—with sizes ranging from 0 to
potassium lithium lithium-ion battery magnesium molybdenum manganese sodium LiNi1−x−yMnxCoyO2 nickel phosphorus particulate matter sulfur antimony silicon tin state of charge strontium titanium zirconium zinc vanadium
0.85 mm, 0.85–1.70 mm, 1.70–2.00 mm, and 2.00–8.00 mm, respectively. The size distribution and elemental composition were measured. These results are conducive to laying the foundation for improving the LIB fire safety by suppressing high_ temperature PM. In addition, these results will reveal the potential harm of the settleable PM released by LIBs to the water and soil. 2. Experimental procedure 2.1. Experimental setup A commercial cell based on NMC cathodes was tested, which is especially for electric automotive. According to the manufacturer's data, the cell nominal capacity and voltage is 50 Ah and 3.65 V, respectively. More information is shown in Table 1. The cell was composed of a lid, a shell and a core. The safety valve, tab and terminal of the cell were installed on the lid. The cathode, separator, and anode were curled to form the core. The cathode was composed of a cathode active material (CAM) and a cathode current collector (CCC). The CAM of the cell in this research was mainly Li (Ni0.6Mn0.2Co0.2) O2, and the current collector was an aluminum foil. Similarly, the anode was composed of an anode active material (AAM) and the anode current collector (ACC). The AAM of the cell in this research was mainly graphite, and the current collector was a copper foil. Table 1 Detailed technical specifications of the test cell.
2
Parameters
Specifications
Cell mass (g) Nominal capacity (Ah) Nominal voltage (V) Minimum voltage (V) Maximum voltage (V) Cathode active material Cathode coating thickness (μm) Anode active material Anode coating thickness (μm) Cathode current collector Cathode current collector thickness (μm) Anode current collector Anode current collector thickness (μm) Shell Material
900 50 3.65 2.75 4.25 Li(Ni0.6Mn0.2Co0.2)O2 61 Graphite 73 Aluminum foil 16 Copper foil 10 Aluminium alloy
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of the LIB vent gases, thereby improving LIB fire safety. The key parameter of the particle filler is its pore size; when the particle size is larger than the pore size, the particulate matter will be trapped. Therefore, the size distribution of particles released by LIBs was researched. Fig. 5 shows the mass of each sample. The total mass of the settleable PM was 97.47 g, accounting for 11.20% of the cell mass, wherein samples a, b, c and d accounted for 4.91%, 4.07%, 0.99%, and 1.23% respectively. The mass percentages of samples a, b, c and d in all particles were 43.79%, 36.37%, 8.88%, and 10.96% respectively. The results show that if a filter with a pore size below 0.85 mm was used, more than 50% of the settleable PM would be filtered. Moreover, large, high-temperature particles would not be released to the outside with the flow. This reduces the risk of high-temperature particles igniting the combustible gases released by the cell in an aerobic environment. Fig. 6 shows the particle size distribution of sample a. As the particle equivalent particle size increased, the particle volume first increased, then decreased, peaking at 339.653 μm of the equivalent particle size. This phenomenon is primarily due to the fact that very small particles of approximately 1 μm will be suspended in the air to form suspended particles, whereas particles close to the diameter of the plug hole may be separated into sample b. The D10 value in sample a was 22.550 μm, i.e., particles with an equivalent particle diameter of less than 22.550 μm account for 10% of the total volume of the particles. Similarly, D50 and D90 were 198.122 μm and 457.047 μm, respectively. The above results indicate that 90%, 50%, and 10% of the particles can be filtered when sample a is filtered using filter holes with diameters of 22.550 μm, 198.122 μm, and 457.047 μm, respectively.
The thermal runaway was triggered by a heater. During the experiment, the cell was placed above the heater and fixed with two hard refractory cottons on the two sides of the cell, as shown in Fig. 1. In order to ensure safety and collect the settleable PM released by the cell, the thermal runaway experiment was conducted in a self-made sealed chamber, as shown in Fig. 2. To observe the venting particles during thermal runaway of the cell, a visualization window was installed in the wall of the sealed chamber. The outer surface of the sealed chamber was covered with insulating cotton to reduce heat transfer. 2.2. Experimental methods The cell SOC for this research was set to 100%, which is the most typical operation. The cell was fully charged under standard conditions before the test was started. The experiment consisted of the following steps. The cell underwent an open circuit voltage check, was charged to the selected SOC, then placed on top of the heater and fixed with hard refractory cottons. The heater was attached inside the sealed chamber and the thermal runaway experiment was initiated by turning on the heater. The cell inside the chamber was heated with a heating power of 1 kW. The cell transited into thermal runaway and venting particles were released alone with the ejection flow. It should be noted that the cell was no longer working properly after the thermal runaway, as shown in Fig. 3. All settleable PM in the chamber were collected after the thermal runaway reaction, and were divided into four samples (a, b, c, and d), as shown in Fig. 4. The collected particles were divided into four parts (a, b, c, and d) using 10-mesh, 12-mesh, and 20-mesh sieves, with corresponding sieve mesh diameters of 0.85 mm, 1.70 mm, and 2.00 mm, as shown in Fig. 4. The maximum size of the particles was 8 mm, measured by a ruler. Therefore, the sizes of the four sample particles ranged from 0 to 0.85 mm, 0.85–1.70 mm, 1.70–2.00 mm, and 2.00–8.00 mm, respectively. The mass was detected by a million-point electronic balance (Sartorius, Germany; BSA224S). The particle size distribution was analyzed by a Malvern particle size analyzer (Malvern Panalytical, United Kingdom; Hydro2000MU). Carbon (C) and sulfur (S) contents were detected by an element analyzer (Elementar Analysensysteme, Germany; Vario EL cube) with a detection limit of 0.01%. Fluorine (F) content was detected by a tester (Dionex, America; ICS-2000) with a detection limit of 1 mg/kg. Elements including phosphorus (P), silicon (Si), boron (B), and non-radioactive metallic elements of the periodic table were detected by an inductively coupled plasma mass spectrometer (Agilent Technologies Inc., America; Agilent-7900) with a detection limit of 1 mg/kg. The Dumas method, gas dynamic separation technology, ion chromatography, and inductively coupled plasma mass spectrometry are widely used methods and have high precision [43–45].
3.2. Elemental composition Table 2 shows the mass and mass percentage of different elements found in each sample. In order to describe the mass percentages of constituent elements in each sample more intuitively, these elements were classified according to the percentages in the total PM, i.e. the overall mass percentage, from high to low, above 1% as shown in Fig. 7(a), between 0.05% and 1% as shown in Fig. 7(b), between 0.005% and 0.05% as shown in Fig. 7(c), and below 0.005% as shown in Fig. 7(d). As shown in Fig. 7(a), the constituent elements with an overall mass percentage of more than 1% included C, nickel (Ni), copper (Cu), cobalt (Co), manganese (Mn), aluminum (Al), and lithium (Li), which accounted for 30.21%, 17.19%, 7.08%, 5.59%, 4.94%, 4.00%, and 3.05%, respectively. It should be noted that the molar ratio of Ni-Mn-Co is very close to 6:2:2, which is the molar ratio of these three elements in the CAM of the cell. As shown in Fig. 7(b), the constituent elements with an overall mass percentage between 0.05% and 1% were potassium (K), P,
3. Results and discussion 3.1. Size distribution According to the thermal ignition theory, a fire requires at least three factors, i.e. fuel, oxidant, and an ignition source. The LIB venting jet caused by the thermal runaway often contains combustible gases and high-temperature PM (e.g. spark). These gases and particles could be the fuel and ignition source of a fire. When the vent gas and vent particles are simultaneously exposed to the outside air (oxidant), the LIB is highly likely to ignite. In addition, as high-temperature particulate matter has large kinetic energy, it is scattered around and in contact with combustible materials, making it highly to catch a fire. Therefore, if the vent PM are trapped by some methods such as using a particle filler, they can be prevented from simultaneously contacting the outside air with the vent gases, thereby failing to satisfy the three elements of the fire. This will greatly reduce the possibility of ignition
Fig. 1. Photograph of the heater and cell used in the test. 3
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Fig. 5. Mass of four samples. Fig. 2. Photograph of the sealed chamber.
Fig. 6. Particle volume distribution of sample a.
more species of constituent elements, especially metallic elements. The metallic elements accounted for 42.9% of the total settleable PM mass, as shown in Fig. 8. Therefore, it is necessary to carefully evaluate the hazards that may arise from PM ejected by LIBs. Among the four samples, sample a had the smallest size of particles, followed by samples b and c, and sample d was the largest. The first two constituent elements with the highest contents were C and Ni for samples a, b and c, and C and Cu for sample d, as shown in Fig. 7(a). In samples a, b and c, the mass percentage of each of the 20 elements, Ni, Co, Mn, Al, Li, K, P, Fe, Na, Ca, Sr, Cr, Ti, Zr, B, Mo, Zn, Mg, Sn, and Ba, was lager compared with that in sample d. The contents of each of the five elements, C, Cu, Si, Sb and F, were smaller, and those of the remaining two elements, S and V, were nearly the same as the four samples. In addition, in samples a, b and c, the total mass percentage of metallic elements was larger than that in sample d. The content of metallic elements in each sample varied between 30% and 50%, as
Fig. 3. Photograph of the cell after thermal runaway.
S, iron (Fe), sodium (Na), and calcium (Ca), and the corresponding percentages were 0.54%, 0.37%, 0.30%, 0.26%, 0.07%, and 0.06%. The percentages of elements in the total settleable PM, including strontium (Sr), chromium (Cr), Si, titanium (Ti), zirconium (Zr), B, molybdenum (Mo), zinc (Zn), magnesium (Mg), antimony (Sb), F, vanadium (V), tin (Sn), and barium (Ba), were all less than 0.05%, as shown in Fig. 7(c) and (d). No other non-radioactive metallic elements were detected. Compared with general PM, for example, automobile exhaust PM (mainly composed of C, H, O, N and S elements [46]), the LIB PM has
Fig. 4. Photograph of samples. 4
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Table 2 Elemental mass and its mass percentage in each sample.
Ele.
Overall 0 < d ≤ 8.00 (g)
C Ni Cu Co Mn Al Li K P S Fe Na Ca Sr Cr Si Ti Zr B Mo Zn Mg Sb F V Sn Ba
29.441 16.754 5.428 4.819 2.976 6.897 3.903 0.526 0.356 0.293 0.258 0.064 0.058 0.044 0.036 0.022 0.007 0.005 0.004 0.004 0.004 0.004 0.003 0.002 0.001 0.001 0.001
(%)
a 0 < d ≤ 0.85 (g)
30.206 17.189 7.076 5.569 4.944 4.005 3.053 0.539 0.366 0.300 0.264 0.066 0.060 0.045 0.037 0.022 0.007 0.005 0.004 0.004 0.004 0.004 0.004 0.002 0.001 0.001 0.001
12.838 7.736 2.521 2.239 1.239 2.452 1.549 0.232 0.235 0.110 0.215 0.030 0.018 0.012 0.031 0.010 0.005 0.003 0.002 0.003 0.003 0.001 0.002 0.001 0.001 0.000 0.000
(%)
b 0.85 < d ≤ 1.70 (g) (%)
c 1.70 < d ≤ 2.00 (g) (%)
d 2.00 < d ≤ 8.00 (g) (%)
30.080 18.126 5.745 5.907 5.245 3.629 2.903 0.544 0.550 0.258 0.505 0.071 0.043 0.028 0.073 0.025 0.011 0.006 0.006 0.008 0.007 0.002 0.004 0.002 0.001 0.001 0.001
10.458 6.808 2.189 1.947 1.312 1.640 1.833 0.224 0.100 0.131 0.029 0.024 0.033 0.024 0.003 0.006 0.001 0.001 0.001 0.000 0.001 0.002 0.001 0.000 0.000 0.000 0.000
1.425 1.913 0.620 0.547 0.315 0.408 0.407 0.056 0.021 0.023 0.008 0.006 0.005 0.007 0.001 0.001 0.000 0.000 0.000 0.000 0.000 0.001 0.000 0.000 0.000 0.000 0.000
4.719 0.298 0.098 0.086 0.110 2.397 0.115 0.014 0.000 0.028 0.006 0.004 0.002 0.001 0.001 0.004 0.000 0.000 0.000 0.000 0.000 0.000 0.001 0.000 0.000 0.000 0.000
29.500 19.202 4.626 6.175 5.492 5.169 3.699 0.632 0.283 0.370 0.081 0.067 0.092 0.067 0.009 0.017 0.003 0.004 0.004 0.001 0.002 0.006 0.003 0.000 0.001 0.001 0.001
Fig. 7. Elemental composition of each sample. 5
16.470 22.098 4.711 7.162 6.325 4.702 3.638 0.643 0.247 0.270 0.087 0.068 0.056 0.080 0.009 0.016 0.004 0.004 0.003 0.001 0.001 0.007 0.003 0.005 0.001 0.001 0.000
44.180 2.785 22.444 0.914 0.805 1.075 1.031 0.129 0.000 0.260 0.054 0.040 0.022 0.011 0.006 0.036 0.004 0.001 0.003 0.001 0.001 0.003 0.005 0.003 0.001 0.001 0.000
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trap them. In other words, the filter should have better performance for both of fire safety and environmental protection. 4. Conclusions The particle size distribution and elemental composition of the settleable solid particles released during thermal runaway of a 50 Ah, 3.65 V lithium-ion battery with an NMC cathode were studied. The main conclusions are summarized as follows: 1) The total mass of the scattered particles is 97.47 g, which accounts for 11.20% of the cell weight. The mass ratios of the four samples, a, b, c and d, with particle sizes ranging from 0_0.85 mm, 0.85_1.70 mm, 1.70_2.00 mm, and 2.00_8.00 mm in all settleable PM are 43.79%, 36.37%, 8.88%, and 10.96%, respectively. 2) For sample a with equivalent particle size below 0.85 mm, as the equivalent particle size increases, the particle volume first increases and then decreases, and peaks when the equivalent particle size is 339.653 μm. D10, D50, and D90 are 22.550 μm, 198.122 μm, and 457.047 μm, respectively. 3) The main constituent elements of the settleable PM are C, Ni, Cu, Co, Mn, Al and Li. The content of metallic elements in each sample varied between 30% and 50%. 4) The first two constituent elements with the highest content are C and Ni for samples a, b and c, and are C and Cu for sample d. In samples a, b and c, the mass percentage of each of the 20 elements, Ni, Co, Mn, Al, Li, K, P, Fe, Na, Ca, Sr, Cr, Ti, Zr, B, Mo, Zn, Mg, Sn and Ba, was lager compared with those in sample d. In samples a, b and c, the contents of each of five elements, C, Cu, Si, Sb and F, were smaller than that in sample d. The remaining two elements, S and V, are almost the same as the four samples. 5) The settleable particles contain elements that are potentially toxic to the human body, such as Al, Li, F and Sn, with corresponding mass percentages of 6.9%, 3.9%, 0.002% and 0.001%, respectively.
Fig. 8. Mass percentages of metallic elements and non-metallic elements in each sample.
shown in Fig. 8. It should be noted that particles contain elements [47,48] such as Al, Li, F and Sn, which are potentially toxic to the human body, with mass percentages of 6.9%, 3.9%, 0.002%, and 0.001%, respectively. They can be enriched thousands of times by biomagnification of the food chain before they finally enter the human body [47]. Therefore, the particles released by the LIB after the thermal runaway must be collected and treated to avoid entering the ecological environment, such as water and soil. These particles are mainly derived from the internal material of the cell, so the correspondence between the particles and cell parts can be established depending on the element source. C is mainly from the AAM of the cell. All the elements of NMC are mainly from the CAM of the cell. Cu is mainly from the ACC. Al is mainly from the CCC of the cell, and Li is present in the CAM, the AAM and the electrolyte. Other remaining elements are from other parts. Therefore, based on the source of these elements, the results of clustering the detected elements are shown in Fig. 9. From the results, it was known that for samples with small particle size, such as a, b and c, the constituent elements were predominantly from the CAM and AAM; for samples with larger particle size, such as sample d, the constituent elements were predominantly from the AAM and its current collector.
Declaration of Competing Interest None. Acknowledgments This research was supported by the Ministry of Science and Technology of the People’s Republic of China under the grant no. 2019YFE010186, the China Postdoctoral Science Foundation under the grant no. 2018M631464, and the National Natural Science Foundation of China under the grant no. U1564205.
3.3. Application Table 3 shows the application of this research. Firstly, studying the particle mass and size distributions of the settleable PM in the process of LIB thermal runaway can provide guidance on how to suppress sparks and reduce the fire risk by reducing the fire source, as well as establish a fire safety active control strategy for LIBs, as discussed in 3.1 Section. From the results, it can be concluded that if a filter with a pore size below 0.85 mm was used, more than 50% of the settleable PM would be filtered out. Approximately 90%, 50%, and 10% of the particles below 0.85 mm can be filtered using filter holes with diameters of 22.550 μm, 198.122 μm, and 457.047 μm, respectively. Secondly, revealing the constituent element of the settleable PM can lay the foundation of proper handling of the LIB fire residue. The results show that these particles contain elements that are potentially toxic to the human body [47,48], such as Al, Li, F and Sn, with mass percentages of 6.9%, 3.9%, 0.002%, and 0.001%, respectively. They can be enriched thousands of times over by biomagnification of the food chain before finally entering the human body [47]. Therefore, these particles from batteries should not be directly released into the natural environment. It should be noted that, if the particle size is smaller, it will be more difficult to
Fig. 9. Mass percentages of elements from LIB parts in each sample. 6
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Table 3 Summary of applications of this research. Characteristic
Section
Application
Related conclusion
Size distribution
3.1
Industrial application: controlling of high-temperature ignition source in lithium-ion battery/electric vehicle fire
Element composition
3.2
Environmental application: proper disposal of settleable PM released by lithium ion batteries
a) If a filter with a pore size below 0.85 mm was used, more than 50% of the settleable PM would be filtered out. b) Approximately 90%, 50%, and 10% of the particles below 0.85 mm can be filtered out using filter holes with diameters of 22.550 μm, 198.122 μm, and 457.047 μm, respectively. a) These particles contain elements [47, 48] that potentially toxic to the human body, including Al, Li, F and Sn. b) The mass percentages of the particles of Al, Li, F and Sn are 6.9%, 3.9%, 0.002% and 0.001%, respectively.
Supplementary materials
[25] A.W. Golubkov, Fuchs D, J. Wagner, H. Wiltsche, C. Stangl, G. Fauler, G. Voitic, A. Thaler, V. Hacker, Thermal-runaway experiments on consumer Li-ion batteries with metal-oxide and olivin-type cathodes, RSC Adv. 4 (2013) 3633–3642. [26] A.W. Golubkov, S. Scheikl, R. Planteu, G. Voitic, H. Wiltsche, C. Stangl, G. Fauler d, A. Thaler, V. Hacker, Thermal runaway of commercial 18650 Li-ion batteries with LFP and NCA cathodes - impact of state of charge and overcharge, RSC Adv. 5 (2015) 57171–57186. [27] D. Xiong, Surprising Chemistry in Li-ion Cells, Dalhousie University, Halifax, 2017. [28] R. Spotnitz, J. Franklin, Abuse behavior of high-power, lithium-ion cells, J. Power Sources 113 (2003) 81–100. [29] M.N. Richard, J.R. Dahn, Accelerating rate calorimetry study on the thermal stability of lithium intercalated graphite in electrolyte. I. Experimental, Fuel Energ. Abs. 41 (1999) 2068–2077. [30] H. Wang, A. Dang, K. Huang, Oxygen evolution in overcharged LixNi1/3Co1/3Mn1/ 3O2 electrode and its thermal analysis kinetics, Hubei Elec. Power 29 (2011) 1583–1588. [31] D.D. MacNeil, J.R. Dahn, The reaction of charged cathodes with nonaqueous solvents and electrolytes: i. Li0.5CoO2, J. Electrochem. Soc. 148 (2001) A1205–A1210. [32] Q. Wang, J. Sun, C. Chen, Thermal stability of delithiated with electrolyte for lithium-ion batteries, J. Electrochem. Soc. 154 (2007) A263–A267. [33] S.E. Sloop, J.K. Pugh, S. Wang, J.B. Kerr, K. Kinoshita, Chemical reactivity of PF5 and LiPF6 in ethylene carbonate/dimethyl carbonate solutions, Electrochem. Solid St. 4 (2001) 357–364. [34] A.D. Pasquier, F. Disma, T. Bowmer, A.S. Gozdz, G. Amatucci, J.M. Tarascon, Differential scanning calorimetry study of the reactivity of carbon anodes in plastic Li-ion batteries, J. Electrochem. Soc. 145 (1998) 472–477. [35] M. Chen, R. Yuen, J. Wang, An experimental study about the effect of arrangement on the fire behaviors of lithium-ion batteries, J. Therm. Anal. Calorim. 129 (2017) 181–188. [36] Q. Zhang, C. Guo, S. Qin, Study on lithium-ion batteries explosive characteristics and aviation transportation safety, J. China Saf. Sci. 26 (2016) 50–55. [37] T. Xu, S. Hui, Combustion Science, China machine press, Beijing, 2017. [38] M.M. Besli, A.K. Shukla, C. Wei, M. Metzger, J. Alvarado, J. Boell, D. Nordlund, G. Schneider, S. Hellstrom, C. Johnston, J. Christensen, M.M. Doeff, Y. Liu, S. Kuppan, Thermally-driven mesopore formation and oxygen release in delithiated NCA cathode particles, J. Mater. Chem. A. 7 (2019) 12593. [39] L. Mu, Q. Yuan, C. Tian, C. Wei, K. Zhang, J. Liu, P. Pianetta, M.M. Doeff, Y. Liu, F. Lin, Propagation topography of redox phase transformations in heterogeneous layered oxide cathode materials, Nat. Commun. 9 (2018) 2810. [40] P. Yan, J. Zheng, T. Chen, L. Luo, Y. Jiang, K. Wang, M. Sui, J. Zhang, S. Zhang, C. Wang, Coupling of electrochemically triggered thermal and mechanical effects to aggravate failure in a layered cathode, Nat. Commun. 9 (2018) 2437. [41] M. Du, K. Liao, Q. Lua, Z. Shao, Recent advances in the interface engineering of solid-state Li-ion batteries with artificial buffer layers: challenges, materials, construction, and characterization, Energy Environ. Sci. 12 (2019) 1780. [42] X. Wu, Y. Xu, Y. Hu, G. Wu, H. Cheng, Q. Yu, K. Zhang, W. Chen, S. Chen, Microfluidic-spinning construction of blackphosphorus-hybrid microfibres for nonwoven fabrics toward a high energy density flexible supercapacitor, Nat. Commun. 9 (2018) 4573. [43] D.L. Morris, A.W. Tebbe, W.P. Weiss, C. Lee, Short communication: effects of drying and analytical methods on nitrogen concentrations of feeds, feces, milk, and urine of dairy cows, J. Dairy Sci. 102 (6) (2019) 5212–5218. [44] J. Zhou, X.H. Chen, S.D. Pan, J.L. Wang, Y.B. Zheng, J.J. Xu, Y.G. Zhan, Z.X. Cai, M.C. Jin, Contamination status of bisphenol A and its analogues (bisphenol S, F and B) in foodstuffs and the implications for dietary exposure on adult residents in Zhejiang Province, Food Chem. 294 (2019) 160–170. [45] E. Bolea-Fernandez, D. Leite, A. Rua-Ibarz, T. Liu, G. Woods, M. Aramendia, M. Resano, F. Vanhaecke, On the effect of using collision/reaction cell (CRC) technology in single-particle ICP-mass spectrometry (SP-ICP-MS), Anal. Chim. Acta. 1077 (2019) 95–106. [46] T. Lv, Physicochemical Characteristics of Particulate Emission from Compression Ignition Engines and Its Influence on Atmospheric Environment, Shanghai Jiao Tong University, Shanghai, 2012. [47] J.Y. Hu, J.Y. Dai, Advance in studies on human distribution and toxic effects of perfluoroalkyl and polyfluoroalkyl substances, Asian J. Ecotoxicol. 8 (2013) 650–657. [48] X. Yang, Trace Elements and Health, New Observations on Nutritional Health (47th issue): Trace Elements and Health Album 1 (2017).
Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.est.2019.100991. References [1] B. Faessler, P. Kepplinger, J. Petrasch, Field testing of repurposed electric vehicle batteries for price-driven grid balancing, J. Energy Storage 21 (2019) 40–47. [2] Ian .D. Campbell, Krishnakumar. Gopalakrishnan, Monica. Marinescu, et al., Optimising lithium-ion cell design for plug-in hybrid and battery electric vehicles, J. Energy Storage 22 (2019) 228–238. [3] Graham. Mills, Iain. MacGill, Assessing electric vehicle storage, flexibility, and distributed energy resource potential, J. Energy Storage 17 (2018) 357–366. [4] Xiao. Shi, Jian. Pan, Hewu. Wang, Hua. Cai, Battery electric vehicles: what is the minimum range required? Energy 166 (2019) 352–358. [5] T. Korakianitis, A.M. Namasivayam, R.J Crookes, Natural-gas fueled spark-ignition (SI) and compression-ignition (CI) engine performance and emissions, Prog. Energy Combust. Sci. 37 (2011) 89–112. [6] Z. Wang, F. Sun, P. Liu, Electric Vehicle Battery Systems, China machine press, Beijing, 2017. [7] IEA, Global Electric Vehicle (EV) Outlook, (2018) https://www.iea.org/gevo2018/. [8] D. Sturk, L. Hoffmann, A.A. Tidblad, Fire tests on e-vehicle battery cells and packs, Traffic. Inj. Prev. 16 (2015) S159–S164. [9] M. Egelhaaf, D. Kress, D. Wolpert, T. Lange, R. Justen, H. Wilstermann, Firefighting of Li-ion traction batteries, SAE Int. J. Alt. Power 2 (2013) 37–48. [10] L.S. Blikeng, S.H. Agerup, Fire in electric cars, SAE Technical Paper 2015-01-1382. [11] X. Feng, M. Fang, X. He, M. Ouyang, L. Lu, H. Wang, M. Zhang, Thermal runaway features of large format prismatic lithium ion battery using extended volume accelerating rate calorimetry, J. Power Sources 255 (2014) 294–301. [12] D.P. Finegan, E. Darcy, M. Keyser, B. Tjaden, T.M.M. Heenan, R. Jervis, J.J. Bailey, R. Malik, N.T. Vo, O.V. Magdysyuk, R. Atwood, M. Drakopoulos, M. DiMichiel, A. Rack, G. Hinds, D.J.L. Bretta, P.R. Shearing, Characterising thermal runaway within lithium-ion cells by inducing and monitoring internal short circuits, Energy Environ. Sci. 10 (2017) 137–1388. [13] P. Ping, Lithium Ion Battery Thermal Runway and Fire Risk Analysis and the Development on the Safer Battery System, University of science and technology of China, Hefei, 2014. [14] Y. Fu, Studies on Combustion Characteristics of Typical Lithium Ion Battery and Its Electrolyte as Well as Influence Mechanism of Air Transport Environment on them, University of science and technology of China, Hefei, 2017. [15] G. Song, Study on Gas Detection Technology of Lithium Battery Fire in Aircraft Cargo, Civil aviation university of China, Tianjin, 2016. [16] Q. Zhang, S. Qin, X. Luo, G. Song, Contrastive analysis of lithium battery's vent gas detection effect in air transportation, Fire Sci. Technol. 36 (2017) 352–354. [17] X. Wei, Z. Wang, L. Yang, H. Yang, Research of anode thermal explosion during Liion batteries thermal runaway, Power Technol 33 (2009) 879–883. [18] Y. Chen, Investigation on LiCo1/3Ni1/3Mn1/3O2 Cathode Material and Safety of Lithium-Ion Battery, Tianjin University, Tianjin, 2006. [19] H. Chen, Z. Tang, X. Lu, Research of explosion mechanism of lithium-ion battery, Prog. Chem. 18 (2006) 823–831. [20] X. Feng, M. Ouyang, X. Liu, L. Lu, Y. Xia, X. He, Thermal runaway mechanism of lithium ion battery for electric vehicles: a review, Energy Storage Mater. 10 (2017) 246–267. [21] B. Long, R. Xu, Y. Liu, Gas-flammability testing for Li-ion cells during abusing, Battery 44 (2014) 121–123. [22] V. Somandepalli, K. Marr, Q. Horn, Quantification of combustion hazards of thermal runaway failures in lithium-ion batteries, SAE Int. J. Alt. Power 3 (2014) 98–104. [23] Q.Q. Liu, D.J. Xiong, R. Petibon, C.Y. Du, J.R. Dahn, Gas evolution during unwanted Lithium plating in Li-ion cells with EC-based or EC-free electrolytes, J. Electrochem. Soc. 163 (2016) A3010–A3015. [24] F. Larsson, S. Bertilsson, M. Furlani, I. Albinsson, B.E. Mellander, Gas explosions and thermal runaways during external heating abuse of commercial lithium-ion graphite-LiCoO2 cells at different levels of ageing, J. Power Sources 373 (2018) 220–231.
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Size distribution and elemental composition of vent particles from abused prismatic Ni-rich automotive lithium-ion batteries
T
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Yajun Zhang, Hewu Wang, Weifeng Li , Cheng Li, Minggao Ouyang State Key Laboratory of Automotive Safety and Energy, Tsinghua University, Beijing 100084, PR China
A R T I C LE I N FO
A B S T R A C T
Keywords: Lithium-ion batteries Settleable PM Particle size distribution Element
The lithium-ion battery (LIB) jet is often accompanied by particulate matter (PM) (e.g. spark) during vent and combustion caused by thermal runaway. These hot PM could ignite the combustible vent gases, and the settleable matter may promote water and soil pollution. The aim of this study is to reveal the statistical size distribution and elemental composition of the settleable PM released by LIBs after thermal runaway. A fully charged commercial 50 Ah Li(Ni0.6Mn0.2Co0.2)O2 cell was triggered by heating in a sealed chamber. These PM were divided into 4 samples using sieves. The sizes were analyzed and the elements were detected. The results show that these PM account for 11.20% of the cell mass. Nearly 45% of particles by mass were found to have a size less than 0.85 mm, with the median size being approximately 198 um. The main elements are carbon, nickel, cobalt, etc. The content of metallic elements is approximately 40%. The emissions also contain potentially toxic elements, including aluminum, lithium, fluorine, etc. The element species in different samples are similar, but their contents differ. The size distribution provides a basis for the design of the particle filter pore, and elemental composition reveals the pollution of LIB emissions.
1. Introduction In recent years, regulatory restrictions on emissions and environmental awareness have prompted a surge in battery electric vehicles and plug-in hybrid electric vehicles and have led to reductions in the usage of traditional internal combustion engine vehicles [1–5]. After many years of development, lithium-ion batteries (LIBs) have become increasingly acceptable as the main power source in vehicles due to their higher energy density, longer calendar or cycle life, and increased reliability [6]. The global stock of electric cars and plug-in hybrid electric vehicles surpassed the 3 million mark in 2017, accompanied by an average annual increase of 56% in 2015 and 2016 (1.2 million and 2 million, respectively) according to the International Energy Agency [7]. Safety aspects concerning these vehicles have also received increasing research attention, such as gas or smoke venting hazards related to failures of on-board large-capacity power batteries, which are difficult to firefight [8–10]. One major battery failure mode is called thermal runaway, where an increase in temperature changes conditions, driving a further increase in temperature [11,12]. The battery vent gas released by LIB in the process of thermal runaway is a key fire hazard [6]. Therefore, many researchers have studied the formation mechanisms of vent gas, as well as the effects of state of charge (SOC), battery type, and battery aging on the ⁎
components and amount of vent gas [13–27]. Vent gas primarily forms from the decomposition of negative solid-electrolyte interface film [28,29], reactions between the anodes and electrolytes [28], decomposition of cathode materials [28,30–32], decomposition of electrolytes [33], decomposition of binders [34], and reactions between various material decomposition products. Somandepalli et al. [22] studied variations in the composition, concentration, and volume of vent gas under different SOCs. They placed the battery in a sealed 6-L chamber filled with argon (Ar) and heated it until vent. The results showed that the gaseous vents mainly included carbon dioxide (CO2), carbon monoxide (CO), hydrogen (H2), and hydrocarbons with different numbers of carbon atoms such as methane (CH4), ethylene (C2H4), and ethane (C2H6). As the SOC increased, the CO2 concentration decreased, the CO and CH4 concentrations increased, the H2 concentration remained relatively unchanged, and total hydrocarbons varied between 20% and 30%. The normalized volume of gaseous vents increased with increasing SOC. In addition to electrolytes and other combustible gases, the battery jet is often accompanied by high-temperature particle matter (PM) during venting and combustion [35,36]. These high-temperature particles are often accompanied by sparks with temperatures as high as 1200 °C [37]. Once the combustible mixture and high-temperature particles have been simultaneously released into the external
Corresponding author. E-mail address: [email protected] (W. Li).
https://doi.org/10.1016/j.est.2019.100991 Received 1 August 2019; Received in revised form 11 September 2019; Accepted 28 September 2019 2352-152X/ © 2019 Elsevier Ltd. All rights reserved.
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Nomenclature AAM ACC Ar Al B Ba C Ca CAM CCC CO2 CO CH4 C2H4 C2H6 Cu Co Cr F Fe
K Li LIB Mg Mo Mn Na NMC Ni P PM S Sb Si Sn SOC Sr Ti Zr Zn V
anode active material anode current collector argon aluminum boron barium carbon calcium cathode active material cathode current collector carbon dioxide carbon monoxide methane ethylene ethane copper cobalt chromium fluorine iron
environment and exposed to oxygen, fire or even explosion could occur [37]. In addition, because high-temperature particulate has large kinetic energy, it is easily scattered and exposed to combustible materials, making it vulnerable to catching fire. Studying the particle size distribution characteristics of settleable PM ejected by LIBs can provide guidance on how to suppress sparks and decrease inflammability by reducing the fire source, as well as establish a fire safety active control strategy for LIBs. In addition, revealing the elemental composition and major components of the settleable PM can allow proper handling of the residue from a LIB fire; i.e., whether it can be directly in contact with human skin, whether it can be released into the natural environment, etc. However, although there have been studies on the phenomenon of venting high-temperature particles during the LIB thermal runaway process, it has not been studied in detail. The particle size distribution and elemental composition of the particles released by LIBs remain unclear. It should be noted that particles released by LIBs are a result of the combined action of all materials inside the battery, so the formation process needs further research, and will not be studied in this paper. Fortunately, the cathode particles’ behavior under thermal abuse conditions has been thoroughly studied and well-documented in the literature [38–40]. For example, Besli et al. [38] investigated the thermal decomposition, fracture, and oxygen evolution of chemically de-lithiated Li0.3Ni0.8Co0.15Al0.05O2 particles upon heating from 25 °C to 450 °C using a number of advanced X-ray and electron probes, and observed a continuous reduction of the Ni oxidation state upon heating, as well as the release of oxygen from the NCA lattice undergoing thermally induced phase transformations. In addition, recent advances [41,42] in the interface engineering of solid-state Li-ion batteries from a microscopic perspective provide sound research methods for researchers to study the PM released by LIBs. The purpose of this research is to reveal the size distribution and elemental composition of the settleable particulate matter released by LIBs during thermal runaway. With this in mind, a 50 Ah, 3.65 V, commercial prismatic LIB cell with lithium nickel manganate cobalt (NMC) oxide cathode was used, and it was placed in a sealed chamber and heated by a 1 kW heater at 100% SOC to trigger the thermal runaway. At the termination of the experiment, the particles scattered throughout the sealed chamber during the battery venting caused by thermal runaway were collected. The settleable PM collected were divided into four samples—a, b, c and d—with sizes ranging from 0 to
potassium lithium lithium-ion battery magnesium molybdenum manganese sodium LiNi1−x−yMnxCoyO2 nickel phosphorus particulate matter sulfur antimony silicon tin state of charge strontium titanium zirconium zinc vanadium
0.85 mm, 0.85–1.70 mm, 1.70–2.00 mm, and 2.00–8.00 mm, respectively. The size distribution and elemental composition were measured. These results are conducive to laying the foundation for improving the LIB fire safety by suppressing high_ temperature PM. In addition, these results will reveal the potential harm of the settleable PM released by LIBs to the water and soil. 2. Experimental procedure 2.1. Experimental setup A commercial cell based on NMC cathodes was tested, which is especially for electric automotive. According to the manufacturer's data, the cell nominal capacity and voltage is 50 Ah and 3.65 V, respectively. More information is shown in Table 1. The cell was composed of a lid, a shell and a core. The safety valve, tab and terminal of the cell were installed on the lid. The cathode, separator, and anode were curled to form the core. The cathode was composed of a cathode active material (CAM) and a cathode current collector (CCC). The CAM of the cell in this research was mainly Li (Ni0.6Mn0.2Co0.2) O2, and the current collector was an aluminum foil. Similarly, the anode was composed of an anode active material (AAM) and the anode current collector (ACC). The AAM of the cell in this research was mainly graphite, and the current collector was a copper foil. Table 1 Detailed technical specifications of the test cell.
2
Parameters
Specifications
Cell mass (g) Nominal capacity (Ah) Nominal voltage (V) Minimum voltage (V) Maximum voltage (V) Cathode active material Cathode coating thickness (μm) Anode active material Anode coating thickness (μm) Cathode current collector Cathode current collector thickness (μm) Anode current collector Anode current collector thickness (μm) Shell Material
900 50 3.65 2.75 4.25 Li(Ni0.6Mn0.2Co0.2)O2 61 Graphite 73 Aluminum foil 16 Copper foil 10 Aluminium alloy
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of the LIB vent gases, thereby improving LIB fire safety. The key parameter of the particle filler is its pore size; when the particle size is larger than the pore size, the particulate matter will be trapped. Therefore, the size distribution of particles released by LIBs was researched. Fig. 5 shows the mass of each sample. The total mass of the settleable PM was 97.47 g, accounting for 11.20% of the cell mass, wherein samples a, b, c and d accounted for 4.91%, 4.07%, 0.99%, and 1.23% respectively. The mass percentages of samples a, b, c and d in all particles were 43.79%, 36.37%, 8.88%, and 10.96% respectively. The results show that if a filter with a pore size below 0.85 mm was used, more than 50% of the settleable PM would be filtered. Moreover, large, high-temperature particles would not be released to the outside with the flow. This reduces the risk of high-temperature particles igniting the combustible gases released by the cell in an aerobic environment. Fig. 6 shows the particle size distribution of sample a. As the particle equivalent particle size increased, the particle volume first increased, then decreased, peaking at 339.653 μm of the equivalent particle size. This phenomenon is primarily due to the fact that very small particles of approximately 1 μm will be suspended in the air to form suspended particles, whereas particles close to the diameter of the plug hole may be separated into sample b. The D10 value in sample a was 22.550 μm, i.e., particles with an equivalent particle diameter of less than 22.550 μm account for 10% of the total volume of the particles. Similarly, D50 and D90 were 198.122 μm and 457.047 μm, respectively. The above results indicate that 90%, 50%, and 10% of the particles can be filtered when sample a is filtered using filter holes with diameters of 22.550 μm, 198.122 μm, and 457.047 μm, respectively.
The thermal runaway was triggered by a heater. During the experiment, the cell was placed above the heater and fixed with two hard refractory cottons on the two sides of the cell, as shown in Fig. 1. In order to ensure safety and collect the settleable PM released by the cell, the thermal runaway experiment was conducted in a self-made sealed chamber, as shown in Fig. 2. To observe the venting particles during thermal runaway of the cell, a visualization window was installed in the wall of the sealed chamber. The outer surface of the sealed chamber was covered with insulating cotton to reduce heat transfer. 2.2. Experimental methods The cell SOC for this research was set to 100%, which is the most typical operation. The cell was fully charged under standard conditions before the test was started. The experiment consisted of the following steps. The cell underwent an open circuit voltage check, was charged to the selected SOC, then placed on top of the heater and fixed with hard refractory cottons. The heater was attached inside the sealed chamber and the thermal runaway experiment was initiated by turning on the heater. The cell inside the chamber was heated with a heating power of 1 kW. The cell transited into thermal runaway and venting particles were released alone with the ejection flow. It should be noted that the cell was no longer working properly after the thermal runaway, as shown in Fig. 3. All settleable PM in the chamber were collected after the thermal runaway reaction, and were divided into four samples (a, b, c, and d), as shown in Fig. 4. The collected particles were divided into four parts (a, b, c, and d) using 10-mesh, 12-mesh, and 20-mesh sieves, with corresponding sieve mesh diameters of 0.85 mm, 1.70 mm, and 2.00 mm, as shown in Fig. 4. The maximum size of the particles was 8 mm, measured by a ruler. Therefore, the sizes of the four sample particles ranged from 0 to 0.85 mm, 0.85–1.70 mm, 1.70–2.00 mm, and 2.00–8.00 mm, respectively. The mass was detected by a million-point electronic balance (Sartorius, Germany; BSA224S). The particle size distribution was analyzed by a Malvern particle size analyzer (Malvern Panalytical, United Kingdom; Hydro2000MU). Carbon (C) and sulfur (S) contents were detected by an element analyzer (Elementar Analysensysteme, Germany; Vario EL cube) with a detection limit of 0.01%. Fluorine (F) content was detected by a tester (Dionex, America; ICS-2000) with a detection limit of 1 mg/kg. Elements including phosphorus (P), silicon (Si), boron (B), and non-radioactive metallic elements of the periodic table were detected by an inductively coupled plasma mass spectrometer (Agilent Technologies Inc., America; Agilent-7900) with a detection limit of 1 mg/kg. The Dumas method, gas dynamic separation technology, ion chromatography, and inductively coupled plasma mass spectrometry are widely used methods and have high precision [43–45].
3.2. Elemental composition Table 2 shows the mass and mass percentage of different elements found in each sample. In order to describe the mass percentages of constituent elements in each sample more intuitively, these elements were classified according to the percentages in the total PM, i.e. the overall mass percentage, from high to low, above 1% as shown in Fig. 7(a), between 0.05% and 1% as shown in Fig. 7(b), between 0.005% and 0.05% as shown in Fig. 7(c), and below 0.005% as shown in Fig. 7(d). As shown in Fig. 7(a), the constituent elements with an overall mass percentage of more than 1% included C, nickel (Ni), copper (Cu), cobalt (Co), manganese (Mn), aluminum (Al), and lithium (Li), which accounted for 30.21%, 17.19%, 7.08%, 5.59%, 4.94%, 4.00%, and 3.05%, respectively. It should be noted that the molar ratio of Ni-Mn-Co is very close to 6:2:2, which is the molar ratio of these three elements in the CAM of the cell. As shown in Fig. 7(b), the constituent elements with an overall mass percentage between 0.05% and 1% were potassium (K), P,
3. Results and discussion 3.1. Size distribution According to the thermal ignition theory, a fire requires at least three factors, i.e. fuel, oxidant, and an ignition source. The LIB venting jet caused by the thermal runaway often contains combustible gases and high-temperature PM (e.g. spark). These gases and particles could be the fuel and ignition source of a fire. When the vent gas and vent particles are simultaneously exposed to the outside air (oxidant), the LIB is highly likely to ignite. In addition, as high-temperature particulate matter has large kinetic energy, it is scattered around and in contact with combustible materials, making it highly to catch a fire. Therefore, if the vent PM are trapped by some methods such as using a particle filler, they can be prevented from simultaneously contacting the outside air with the vent gases, thereby failing to satisfy the three elements of the fire. This will greatly reduce the possibility of ignition
Fig. 1. Photograph of the heater and cell used in the test. 3
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Fig. 5. Mass of four samples. Fig. 2. Photograph of the sealed chamber.
Fig. 6. Particle volume distribution of sample a.
more species of constituent elements, especially metallic elements. The metallic elements accounted for 42.9% of the total settleable PM mass, as shown in Fig. 8. Therefore, it is necessary to carefully evaluate the hazards that may arise from PM ejected by LIBs. Among the four samples, sample a had the smallest size of particles, followed by samples b and c, and sample d was the largest. The first two constituent elements with the highest contents were C and Ni for samples a, b and c, and C and Cu for sample d, as shown in Fig. 7(a). In samples a, b and c, the mass percentage of each of the 20 elements, Ni, Co, Mn, Al, Li, K, P, Fe, Na, Ca, Sr, Cr, Ti, Zr, B, Mo, Zn, Mg, Sn, and Ba, was lager compared with that in sample d. The contents of each of the five elements, C, Cu, Si, Sb and F, were smaller, and those of the remaining two elements, S and V, were nearly the same as the four samples. In addition, in samples a, b and c, the total mass percentage of metallic elements was larger than that in sample d. The content of metallic elements in each sample varied between 30% and 50%, as
Fig. 3. Photograph of the cell after thermal runaway.
S, iron (Fe), sodium (Na), and calcium (Ca), and the corresponding percentages were 0.54%, 0.37%, 0.30%, 0.26%, 0.07%, and 0.06%. The percentages of elements in the total settleable PM, including strontium (Sr), chromium (Cr), Si, titanium (Ti), zirconium (Zr), B, molybdenum (Mo), zinc (Zn), magnesium (Mg), antimony (Sb), F, vanadium (V), tin (Sn), and barium (Ba), were all less than 0.05%, as shown in Fig. 7(c) and (d). No other non-radioactive metallic elements were detected. Compared with general PM, for example, automobile exhaust PM (mainly composed of C, H, O, N and S elements [46]), the LIB PM has
Fig. 4. Photograph of samples. 4
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Table 2 Elemental mass and its mass percentage in each sample.
Ele.
Overall 0 < d ≤ 8.00 (g)
C Ni Cu Co Mn Al Li K P S Fe Na Ca Sr Cr Si Ti Zr B Mo Zn Mg Sb F V Sn Ba
29.441 16.754 5.428 4.819 2.976 6.897 3.903 0.526 0.356 0.293 0.258 0.064 0.058 0.044 0.036 0.022 0.007 0.005 0.004 0.004 0.004 0.004 0.003 0.002 0.001 0.001 0.001
(%)
a 0 < d ≤ 0.85 (g)
30.206 17.189 7.076 5.569 4.944 4.005 3.053 0.539 0.366 0.300 0.264 0.066 0.060 0.045 0.037 0.022 0.007 0.005 0.004 0.004 0.004 0.004 0.004 0.002 0.001 0.001 0.001
12.838 7.736 2.521 2.239 1.239 2.452 1.549 0.232 0.235 0.110 0.215 0.030 0.018 0.012 0.031 0.010 0.005 0.003 0.002 0.003 0.003 0.001 0.002 0.001 0.001 0.000 0.000
(%)
b 0.85 < d ≤ 1.70 (g) (%)
c 1.70 < d ≤ 2.00 (g) (%)
d 2.00 < d ≤ 8.00 (g) (%)
30.080 18.126 5.745 5.907 5.245 3.629 2.903 0.544 0.550 0.258 0.505 0.071 0.043 0.028 0.073 0.025 0.011 0.006 0.006 0.008 0.007 0.002 0.004 0.002 0.001 0.001 0.001
10.458 6.808 2.189 1.947 1.312 1.640 1.833 0.224 0.100 0.131 0.029 0.024 0.033 0.024 0.003 0.006 0.001 0.001 0.001 0.000 0.001 0.002 0.001 0.000 0.000 0.000 0.000
1.425 1.913 0.620 0.547 0.315 0.408 0.407 0.056 0.021 0.023 0.008 0.006 0.005 0.007 0.001 0.001 0.000 0.000 0.000 0.000 0.000 0.001 0.000 0.000 0.000 0.000 0.000
4.719 0.298 0.098 0.086 0.110 2.397 0.115 0.014 0.000 0.028 0.006 0.004 0.002 0.001 0.001 0.004 0.000 0.000 0.000 0.000 0.000 0.000 0.001 0.000 0.000 0.000 0.000
29.500 19.202 4.626 6.175 5.492 5.169 3.699 0.632 0.283 0.370 0.081 0.067 0.092 0.067 0.009 0.017 0.003 0.004 0.004 0.001 0.002 0.006 0.003 0.000 0.001 0.001 0.001
Fig. 7. Elemental composition of each sample. 5
16.470 22.098 4.711 7.162 6.325 4.702 3.638 0.643 0.247 0.270 0.087 0.068 0.056 0.080 0.009 0.016 0.004 0.004 0.003 0.001 0.001 0.007 0.003 0.005 0.001 0.001 0.000
44.180 2.785 22.444 0.914 0.805 1.075 1.031 0.129 0.000 0.260 0.054 0.040 0.022 0.011 0.006 0.036 0.004 0.001 0.003 0.001 0.001 0.003 0.005 0.003 0.001 0.001 0.000
Journal of Energy Storage 26 (2019) 100991
Y. Zhang, et al.
trap them. In other words, the filter should have better performance for both of fire safety and environmental protection. 4. Conclusions The particle size distribution and elemental composition of the settleable solid particles released during thermal runaway of a 50 Ah, 3.65 V lithium-ion battery with an NMC cathode were studied. The main conclusions are summarized as follows: 1) The total mass of the scattered particles is 97.47 g, which accounts for 11.20% of the cell weight. The mass ratios of the four samples, a, b, c and d, with particle sizes ranging from 0_0.85 mm, 0.85_1.70 mm, 1.70_2.00 mm, and 2.00_8.00 mm in all settleable PM are 43.79%, 36.37%, 8.88%, and 10.96%, respectively. 2) For sample a with equivalent particle size below 0.85 mm, as the equivalent particle size increases, the particle volume first increases and then decreases, and peaks when the equivalent particle size is 339.653 μm. D10, D50, and D90 are 22.550 μm, 198.122 μm, and 457.047 μm, respectively. 3) The main constituent elements of the settleable PM are C, Ni, Cu, Co, Mn, Al and Li. The content of metallic elements in each sample varied between 30% and 50%. 4) The first two constituent elements with the highest content are C and Ni for samples a, b and c, and are C and Cu for sample d. In samples a, b and c, the mass percentage of each of the 20 elements, Ni, Co, Mn, Al, Li, K, P, Fe, Na, Ca, Sr, Cr, Ti, Zr, B, Mo, Zn, Mg, Sn and Ba, was lager compared with those in sample d. In samples a, b and c, the contents of each of five elements, C, Cu, Si, Sb and F, were smaller than that in sample d. The remaining two elements, S and V, are almost the same as the four samples. 5) The settleable particles contain elements that are potentially toxic to the human body, such as Al, Li, F and Sn, with corresponding mass percentages of 6.9%, 3.9%, 0.002% and 0.001%, respectively.
Fig. 8. Mass percentages of metallic elements and non-metallic elements in each sample.
shown in Fig. 8. It should be noted that particles contain elements [47,48] such as Al, Li, F and Sn, which are potentially toxic to the human body, with mass percentages of 6.9%, 3.9%, 0.002%, and 0.001%, respectively. They can be enriched thousands of times by biomagnification of the food chain before they finally enter the human body [47]. Therefore, the particles released by the LIB after the thermal runaway must be collected and treated to avoid entering the ecological environment, such as water and soil. These particles are mainly derived from the internal material of the cell, so the correspondence between the particles and cell parts can be established depending on the element source. C is mainly from the AAM of the cell. All the elements of NMC are mainly from the CAM of the cell. Cu is mainly from the ACC. Al is mainly from the CCC of the cell, and Li is present in the CAM, the AAM and the electrolyte. Other remaining elements are from other parts. Therefore, based on the source of these elements, the results of clustering the detected elements are shown in Fig. 9. From the results, it was known that for samples with small particle size, such as a, b and c, the constituent elements were predominantly from the CAM and AAM; for samples with larger particle size, such as sample d, the constituent elements were predominantly from the AAM and its current collector.
Declaration of Competing Interest None. Acknowledgments This research was supported by the Ministry of Science and Technology of the People’s Republic of China under the grant no. 2019YFE010186, the China Postdoctoral Science Foundation under the grant no. 2018M631464, and the National Natural Science Foundation of China under the grant no. U1564205.
3.3. Application Table 3 shows the application of this research. Firstly, studying the particle mass and size distributions of the settleable PM in the process of LIB thermal runaway can provide guidance on how to suppress sparks and reduce the fire risk by reducing the fire source, as well as establish a fire safety active control strategy for LIBs, as discussed in 3.1 Section. From the results, it can be concluded that if a filter with a pore size below 0.85 mm was used, more than 50% of the settleable PM would be filtered out. Approximately 90%, 50%, and 10% of the particles below 0.85 mm can be filtered using filter holes with diameters of 22.550 μm, 198.122 μm, and 457.047 μm, respectively. Secondly, revealing the constituent element of the settleable PM can lay the foundation of proper handling of the LIB fire residue. The results show that these particles contain elements that are potentially toxic to the human body [47,48], such as Al, Li, F and Sn, with mass percentages of 6.9%, 3.9%, 0.002%, and 0.001%, respectively. They can be enriched thousands of times over by biomagnification of the food chain before finally entering the human body [47]. Therefore, these particles from batteries should not be directly released into the natural environment. It should be noted that, if the particle size is smaller, it will be more difficult to
Fig. 9. Mass percentages of elements from LIB parts in each sample. 6
Journal of Energy Storage 26 (2019) 100991
Y. Zhang, et al.
Table 3 Summary of applications of this research. Characteristic
Section
Application
Related conclusion
Size distribution
3.1
Industrial application: controlling of high-temperature ignition source in lithium-ion battery/electric vehicle fire
Element composition
3.2
Environmental application: proper disposal of settleable PM released by lithium ion batteries
a) If a filter with a pore size below 0.85 mm was used, more than 50% of the settleable PM would be filtered out. b) Approximately 90%, 50%, and 10% of the particles below 0.85 mm can be filtered out using filter holes with diameters of 22.550 μm, 198.122 μm, and 457.047 μm, respectively. a) These particles contain elements [47, 48] that potentially toxic to the human body, including Al, Li, F and Sn. b) The mass percentages of the particles of Al, Li, F and Sn are 6.9%, 3.9%, 0.002% and 0.001%, respectively.
Supplementary materials
[25] A.W. Golubkov, Fuchs D, J. Wagner, H. Wiltsche, C. Stangl, G. Fauler, G. Voitic, A. Thaler, V. Hacker, Thermal-runaway experiments on consumer Li-ion batteries with metal-oxide and olivin-type cathodes, RSC Adv. 4 (2013) 3633–3642. [26] A.W. Golubkov, S. Scheikl, R. Planteu, G. Voitic, H. Wiltsche, C. Stangl, G. Fauler d, A. Thaler, V. Hacker, Thermal runaway of commercial 18650 Li-ion batteries with LFP and NCA cathodes - impact of state of charge and overcharge, RSC Adv. 5 (2015) 57171–57186. [27] D. Xiong, Surprising Chemistry in Li-ion Cells, Dalhousie University, Halifax, 2017. [28] R. Spotnitz, J. Franklin, Abuse behavior of high-power, lithium-ion cells, J. Power Sources 113 (2003) 81–100. [29] M.N. Richard, J.R. Dahn, Accelerating rate calorimetry study on the thermal stability of lithium intercalated graphite in electrolyte. I. Experimental, Fuel Energ. Abs. 41 (1999) 2068–2077. [30] H. Wang, A. Dang, K. Huang, Oxygen evolution in overcharged LixNi1/3Co1/3Mn1/ 3O2 electrode and its thermal analysis kinetics, Hubei Elec. Power 29 (2011) 1583–1588. [31] D.D. MacNeil, J.R. Dahn, The reaction of charged cathodes with nonaqueous solvents and electrolytes: i. Li0.5CoO2, J. Electrochem. Soc. 148 (2001) A1205–A1210. [32] Q. Wang, J. Sun, C. Chen, Thermal stability of delithiated with electrolyte for lithium-ion batteries, J. Electrochem. Soc. 154 (2007) A263–A267. [33] S.E. Sloop, J.K. Pugh, S. Wang, J.B. Kerr, K. Kinoshita, Chemical reactivity of PF5 and LiPF6 in ethylene carbonate/dimethyl carbonate solutions, Electrochem. Solid St. 4 (2001) 357–364. [34] A.D. Pasquier, F. Disma, T. Bowmer, A.S. Gozdz, G. Amatucci, J.M. Tarascon, Differential scanning calorimetry study of the reactivity of carbon anodes in plastic Li-ion batteries, J. Electrochem. Soc. 145 (1998) 472–477. [35] M. Chen, R. Yuen, J. Wang, An experimental study about the effect of arrangement on the fire behaviors of lithium-ion batteries, J. Therm. Anal. Calorim. 129 (2017) 181–188. [36] Q. Zhang, C. Guo, S. Qin, Study on lithium-ion batteries explosive characteristics and aviation transportation safety, J. China Saf. Sci. 26 (2016) 50–55. [37] T. Xu, S. Hui, Combustion Science, China machine press, Beijing, 2017. [38] M.M. Besli, A.K. Shukla, C. Wei, M. Metzger, J. Alvarado, J. Boell, D. Nordlund, G. Schneider, S. Hellstrom, C. Johnston, J. Christensen, M.M. Doeff, Y. Liu, S. Kuppan, Thermally-driven mesopore formation and oxygen release in delithiated NCA cathode particles, J. Mater. Chem. A. 7 (2019) 12593. [39] L. Mu, Q. Yuan, C. Tian, C. Wei, K. Zhang, J. Liu, P. Pianetta, M.M. Doeff, Y. Liu, F. Lin, Propagation topography of redox phase transformations in heterogeneous layered oxide cathode materials, Nat. Commun. 9 (2018) 2810. [40] P. Yan, J. Zheng, T. Chen, L. Luo, Y. Jiang, K. Wang, M. Sui, J. Zhang, S. Zhang, C. Wang, Coupling of electrochemically triggered thermal and mechanical effects to aggravate failure in a layered cathode, Nat. Commun. 9 (2018) 2437. [41] M. Du, K. Liao, Q. Lua, Z. Shao, Recent advances in the interface engineering of solid-state Li-ion batteries with artificial buffer layers: challenges, materials, construction, and characterization, Energy Environ. Sci. 12 (2019) 1780. [42] X. Wu, Y. Xu, Y. Hu, G. Wu, H. Cheng, Q. Yu, K. Zhang, W. Chen, S. Chen, Microfluidic-spinning construction of blackphosphorus-hybrid microfibres for nonwoven fabrics toward a high energy density flexible supercapacitor, Nat. Commun. 9 (2018) 4573. [43] D.L. Morris, A.W. Tebbe, W.P. Weiss, C. Lee, Short communication: effects of drying and analytical methods on nitrogen concentrations of feeds, feces, milk, and urine of dairy cows, J. Dairy Sci. 102 (6) (2019) 5212–5218. [44] J. Zhou, X.H. Chen, S.D. Pan, J.L. Wang, Y.B. Zheng, J.J. Xu, Y.G. Zhan, Z.X. Cai, M.C. Jin, Contamination status of bisphenol A and its analogues (bisphenol S, F and B) in foodstuffs and the implications for dietary exposure on adult residents in Zhejiang Province, Food Chem. 294 (2019) 160–170. [45] E. Bolea-Fernandez, D. Leite, A. Rua-Ibarz, T. Liu, G. Woods, M. Aramendia, M. Resano, F. Vanhaecke, On the effect of using collision/reaction cell (CRC) technology in single-particle ICP-mass spectrometry (SP-ICP-MS), Anal. Chim. Acta. 1077 (2019) 95–106. [46] T. Lv, Physicochemical Characteristics of Particulate Emission from Compression Ignition Engines and Its Influence on Atmospheric Environment, Shanghai Jiao Tong University, Shanghai, 2012. [47] J.Y. Hu, J.Y. Dai, Advance in studies on human distribution and toxic effects of perfluoroalkyl and polyfluoroalkyl substances, Asian J. Ecotoxicol. 8 (2013) 650–657. [48] X. Yang, Trace Elements and Health, New Observations on Nutritional Health (47th issue): Trace Elements and Health Album 1 (2017).
Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.est.2019.100991. References [1] B. Faessler, P. Kepplinger, J. Petrasch, Field testing of repurposed electric vehicle batteries for price-driven grid balancing, J. Energy Storage 21 (2019) 40–47. [2] Ian .D. Campbell, Krishnakumar. Gopalakrishnan, Monica. Marinescu, et al., Optimising lithium-ion cell design for plug-in hybrid and battery electric vehicles, J. Energy Storage 22 (2019) 228–238. [3] Graham. Mills, Iain. MacGill, Assessing electric vehicle storage, flexibility, and distributed energy resource potential, J. Energy Storage 17 (2018) 357–366. [4] Xiao. Shi, Jian. Pan, Hewu. Wang, Hua. Cai, Battery electric vehicles: what is the minimum range required? Energy 166 (2019) 352–358. [5] T. Korakianitis, A.M. Namasivayam, R.J Crookes, Natural-gas fueled spark-ignition (SI) and compression-ignition (CI) engine performance and emissions, Prog. Energy Combust. Sci. 37 (2011) 89–112. [6] Z. Wang, F. Sun, P. Liu, Electric Vehicle Battery Systems, China machine press, Beijing, 2017. [7] IEA, Global Electric Vehicle (EV) Outlook, (2018) https://www.iea.org/gevo2018/. [8] D. Sturk, L. Hoffmann, A.A. Tidblad, Fire tests on e-vehicle battery cells and packs, Traffic. Inj. Prev. 16 (2015) S159–S164. [9] M. Egelhaaf, D. Kress, D. Wolpert, T. Lange, R. Justen, H. Wilstermann, Firefighting of Li-ion traction batteries, SAE Int. J. Alt. Power 2 (2013) 37–48. [10] L.S. Blikeng, S.H. Agerup, Fire in electric cars, SAE Technical Paper 2015-01-1382. [11] X. Feng, M. Fang, X. He, M. Ouyang, L. Lu, H. Wang, M. Zhang, Thermal runaway features of large format prismatic lithium ion battery using extended volume accelerating rate calorimetry, J. Power Sources 255 (2014) 294–301. [12] D.P. Finegan, E. Darcy, M. Keyser, B. Tjaden, T.M.M. Heenan, R. Jervis, J.J. Bailey, R. Malik, N.T. Vo, O.V. Magdysyuk, R. Atwood, M. Drakopoulos, M. DiMichiel, A. Rack, G. Hinds, D.J.L. Bretta, P.R. Shearing, Characterising thermal runaway within lithium-ion cells by inducing and monitoring internal short circuits, Energy Environ. Sci. 10 (2017) 137–1388. [13] P. Ping, Lithium Ion Battery Thermal Runway and Fire Risk Analysis and the Development on the Safer Battery System, University of science and technology of China, Hefei, 2014. [14] Y. Fu, Studies on Combustion Characteristics of Typical Lithium Ion Battery and Its Electrolyte as Well as Influence Mechanism of Air Transport Environment on them, University of science and technology of China, Hefei, 2017. [15] G. Song, Study on Gas Detection Technology of Lithium Battery Fire in Aircraft Cargo, Civil aviation university of China, Tianjin, 2016. [16] Q. Zhang, S. Qin, X. Luo, G. Song, Contrastive analysis of lithium battery's vent gas detection effect in air transportation, Fire Sci. Technol. 36 (2017) 352–354. [17] X. Wei, Z. Wang, L. Yang, H. Yang, Research of anode thermal explosion during Liion batteries thermal runaway, Power Technol 33 (2009) 879–883. [18] Y. Chen, Investigation on LiCo1/3Ni1/3Mn1/3O2 Cathode Material and Safety of Lithium-Ion Battery, Tianjin University, Tianjin, 2006. [19] H. Chen, Z. Tang, X. Lu, Research of explosion mechanism of lithium-ion battery, Prog. Chem. 18 (2006) 823–831. [20] X. Feng, M. Ouyang, X. Liu, L. Lu, Y. Xia, X. He, Thermal runaway mechanism of lithium ion battery for electric vehicles: a review, Energy Storage Mater. 10 (2017) 246–267. [21] B. Long, R. Xu, Y. Liu, Gas-flammability testing for Li-ion cells during abusing, Battery 44 (2014) 121–123. [22] V. Somandepalli, K. Marr, Q. Horn, Quantification of combustion hazards of thermal runaway failures in lithium-ion batteries, SAE Int. J. Alt. Power 3 (2014) 98–104. [23] Q.Q. Liu, D.J. Xiong, R. Petibon, C.Y. Du, J.R. Dahn, Gas evolution during unwanted Lithium plating in Li-ion cells with EC-based or EC-free electrolytes, J. Electrochem. Soc. 163 (2016) A3010–A3015. [24] F. Larsson, S. Bertilsson, M. Furlani, I. Albinsson, B.E. Mellander, Gas explosions and thermal runaways during external heating abuse of commercial lithium-ion graphite-LiCoO2 cells at different levels of ageing, J. Power Sources 373 (2018) 220–231.
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