Why do cell phones catch fire and explode? The answers are here!

One more death due to an explosion of a cellular phone was reported. Despite the several records published until now, are we resigned that nothing can be done and would this be the price to be paid for the use of technology?

Historical

Concerns about the use of cell phones did not birth today. A study published in the United States in 1999 [1] debated the application of mobile phones (of that time) in hazardous areas (industrial locations subjected to the occurrence of an explosive atmosphere, which in this case requires that only special electrical and electronic equipment can be used). The summary of the findings was that?"the use of mobile phones, under normal conditions, in fuel stations, presents a negligible risk, with remote possibilities of causing accidents".

Nevertheless, cities from several countries issued laws prohibiting the use of mobile phones at petrol stations, such as Rio de Janeiro and S?o Paulo [2].

Technical papers presented at international congresses [3], reported that despite the low risk, only specifically designed and certified cell phones could be safely used in hazardous (classified) locations.

Since then, the manufacturers promoted an incessant search for batteries with increasing load densities (mAh/mm3), that is, with higher energy capacity per volume, having emerged in the market the lithium-ion (Li-ion) batteries.

Reports and concerns

The largest laptops' manufacturers have already made recall of thousands of batteries. The video below reports these recalls, as well as shows a Li-ion battery burning after being overheated by an electrical grid placed under the laptop. This is only a laboratory simulation (the victims of real occurrences did not use such grids), but it serves to illustrate the consequences of unfolding the "thermal runaway" phenomenon: fire and explosion of batteries' cells. The incendiary reaction in Lithium batteries with flammable liquid electrolyte has the aggravating that they do not need the oxygen from the environment to feed the flames: everything needed is already in the cell itself. To safely combat such fire, it is recommended do not throw water or put a cloth on it, in case of lithium-metal batteries (see the video below): the recommended action is to use a class D extinguisher (for use in combustible and pyrophoric metals). The speed of the reaction is very fast: in one minute there are already high flames.

Pseudo-causes:

It is easy to find in the press media the attribution of the explosion of cell phones to?"cheaper batteries" and the use of?"non first-party chargers". Although they offer risk due to the lower quality of their components, they cannot be considered as the causes of explosions, since original batteries were already also recalled, as well as in various situations the burned cell phones were in normal use, not on charging. It should be noted that in the case of the Samsung Galaxy Note 7, even on disconnected devices, fires were reported. In the video below, it is shown a Li-ion battery burning after being perforated; in real life, we do not see users sticking their batteries (which consequence is to cause a short circuit), but note that their pets can do it, as shown in the second video below.

Usually we found on the internet inconsistent reports that point to pseudo-causes, such as the record of measurements of?"50 V in the headphone terminals of a cell phone due to a non-original charger". Considering that the cell phone batteries' voltage is 5 V, and even the non-original chargers would operate compulsorily in the same voltage range, it was considered strange such assertion, because if we apply 50 V in a cell phone, the internal components will burn. Subsequently, it was verified that the measurement instrument used in that video was inadequate and presented error in that application, which invalidated the hypothesis!

The real causes

Since cell phone manufacturers were searching for batteries with higher and higher energy density, Li-ion batteries with flammable liquid electrolyte and carbon electrodes emerged, which could reach a total energy density up to 600 Watts-hour per litre (Wh/L) at the cell level.

The most famous case about fires and explosions in cell phones occurred with the Samsung Galaxy Note 7, which after being banned on commercial flights from around the world, suffered a recall of US$ 5 billion and had its manufacturing interrupted in 2016/10/11 [4]. In 2017/1/22, Samsung made the official announcement about the result of its internal investigation, which pointed two causes, originated in the process of manufacturing the batteries (which were acquired from two suppliers, Samsung SDI and Amperex) [5]:

1- Inadequate position of the negative electrode;

2- Inadequate internal welds, with formation of tips that pierced an insulated separator membrane and provoked an internal short-circuit.

However, as several brands and models of cell phones recorded similar occurrences [6], researchers have found that the carbon electrode used in this type of batteries, end up forming nanoscopic structures, called dendrites, which cause internal short-circuits. The dendrites are spiny projections that begin to grow from the electrode's surface that can pierce the membrane separator, promoting a short-circuit inside the cell [7]. That is, the causes would be also chemical, not just mechanical, as pointed by Samsung. And the formation of dendrites could occur throughout the use, not necessarily on recharges. Therefore, contrary to what many can think, the main event is not a short circuit at the external terminals of the battery, but rather, an internal short circuit due to the geometry of the construction and the materials used (which possess an unstable chemical structure, able to promote spontaneous combustion). Thus, as the events continued to occur, more researches were done seeking new alternatives to achieve higher load densities in a safe way [8].

The solutions

Recently, a research has indicated an alternative to solve the problem of combustion of Li-ion batteries: the use of a solid lithium electrolyte and the addition of an interface - a ceramic layer - over the electrode that kept it stabilized during recharges, preventing the dendrites from forming and preventing the batteries from catching fire, even in overload. In principle, the new batteries with solid electrolyte can reach 1,200 Wh/L, and the new technology, as employing ceramic (which is not combustible), has been tested to more than 980 degrees Celsius. And because it does not contain flammable liquid as electrolyte in the battery, this was the first attempt to reduce the possibility of combustion [8]. But, a paper already published, showed that there are exothermic reactions of all solid state cells at a certain temperature, hence showing flammability of the all solid state (ASS) batteries. [9]

Another promising alternative was announced in 2017 by John Goodenough, one of the 2019 Nobel Prize winners for the development of lithium-ion batteries, which uses as a solid electrolyte, glass, eliminating the possibility of dendrites forming, which cause short circuits in li-ion batteries, starting the explosions and fires. [10]

What to do

As we now know, the risks of fires and explosions are due to the technology of Li-ion batteries with flammable liquid electrolyte, which are inherently unstables [11]. The instability is so high that in the factory of these batteries, two to three fires per day are recorded in the assembly line! [12 @ 18': 25"].

And they are not only present in mobile phones, but in various electronic equipment, as laptops, toys (such as skates and hoverboards, which are already banned on planes [13]), e-cigarettes (of which thousands of incidents are been registered [14]) automobiles [15], [16], [17], electric bikes [18], and even smartwatches ![19] The criticality is such, that there are videos showing cell phones catching fires in normal use, and not only on recharging!

The fire and explosions events are not restricted to small batteries, but have been happened also in big Battery Energy Storage Systems (BESS) reported in South Korea, Europe and Australia. The video below shows one more case of fire caused by Li-ion batteries:

FM Global conducts fire researches on li-ion BESS at its research center in West Glocester, Rhode Island [20], and UL issued the standard UL 9540A - Test Method for Evaluating Thermal Runaway Fire Propagation in Battery Energy Storage Systems.

Remember that in the last few years we have seen a string of incidents with li-ion batteries exploding in aircraft or near airports, as the SkyWest flight 4449 on March 2018 [21], and the incident at the Greater Orlando International Airport in the TSA Checkpoint Lane, where a li-ion camera battery had exploded, causing the passenger's bag to catch fire [22].

On August 2019, FAA - the US Federal Aviation Administration - said that under FAA policy, affected MacBook Pros under the Apple's June 2019 recall, were banned from the passenger cabin and from checked luggage, which reaffirms that this problem with li-ion batteries is not solved yet! [23]

Note also that an FAA safety alert from 2016 issued to foreign and domestic carriers warned that “current cargo fire suppression systems cannot effectively control a lithium battery fire.” [24]

From the records of several cases, it would be up to the government regulators (in Brasil, the ANATEL), to disclose them as alerts to the population, as well as suspend the commercialization of the brands and models involved in accidents until the causes were identified and manufacturers notified to provide solutions (as Samsung did) in order to promote safety to citizens! Civil society entities should push government agencies into this direction! [25]

Until an effective action is taken by the authorities, it is worth recommending that users know the type of battery that their devices use and always keep them under surveillance, in conditions of easy access and prompt removal from where they are, avoiding leaving them on easy to burn materials such as sofas, cushions, etc. even if they are not recharging! On the first sign of an abnormal heating, put them on a uncombustible surface, because a thermal runaway - leading to fire and explosions - can be developed in seconds!

Conclusion

The current Li-ion battery technology is unsafe! [26]

References

[1] "Cell phone usage at gasoline stations", Exponent Failure Analysis Associates. Menlo Park, California, USA, December 1999.

[2] Rangel Jr., Estellito - Celulares e áreas classificadas. Eletricidade Moderna Magazine, Section EM Ex (the first Brazilian technical column, monthly published, fully dedicated to installations in hazardous locations), February 2008, pp. 178-180. Available at: https://bit.ly/2CA97lk

[3] Allan Bozek, Ken Martin and Marty Cole - Mobile phones in Category 3 explosive gas atmospheres. 4th European Conference on Electrical and Instrumentation Applications in the Petroleum & Chemical Industry, pp. 122-132, 2007. Available at: https://ieeexplore.ieee.org/document/4353999/

[4] "Samsung Galaxy Note 7 banned on all U.S. flights due to fire hazard", USA Today newspaper, October 14, 2016. Available at: https://www.usatoday.com/story/news/2016/10/14/dot-bans-samsung-galaxy-note-7-flights/92066322/

[5] "Samsung explains why the Galaxy Note 7 exploded", January 22, 2017. Available at: https://youtu.be/mnpF7p37x3I

[6] "Busting the myth: yes, cell phones can explode". Android Authority, January 8, 2008. Available at: https://www.androidauthority.com/busting-the-myth-yes-cell-phones-can-explode-42582/

[7] Melissae Fellet - "Fire-starting battery dendrites go with the flow", The Royal Society of Chemistry, September 4, 2009. Available at: https://www.chemistryworld.com/news/fire-starting-battery-dendrites-go-with-the-flow/3008867.article

[8] Nathan J. Taylor, Sandra Stangeland-Molo, Catherine G. Haslam, Asma Sharafi, Travis Thompson, Michael Wang, Regina Garcia-Mendez, and Jeff Sakamoto - Demonstration of high current densities and extended cycling in the garnet Li7La3Zr2O12 solid electrolyte. Journal of Power Sources, vol.: 396, August 31, 2018, Pages 314-318, DOI: 10.1016/j.jpowsour.2018.06.055 Available at: https://www.researchgate.net/publication/325951639_Demonstration_of_high_current_densities_and_extended_cycling_in_the_garnet_Li7La3Zr2O12_solid_electrolyte

[9] Takao Inoue and Kazuhiko Mukai?- Are all-solid-state lithium-ion batteries really safe? – Verification by differential scanning calorimetry with an all-inclusive microcell. Available at: https://pubs.acs.org/doi/full/10.1021/acsami.6b13224

[10] Lithium-ion battery inventor introduces new technology for fast-charging, noncombustible batteries. UT News, Feb 28, 2017. Available at: https://news.utexas.edu/2017/02/28/goodenough-introduces-new-battery-technology/. Accessed on May 2, 2022.

[11] A. Lahiri, N. Shah and C. Dales - Building a safer, denser lithium-ion battery. IEEE Spectrum, vol. 55 no. 3, pp. 34-39, 2018. Available at: https://ieeexplore.ieee.org/document/8302385/

[12] "Inside an iPhone battery factory - in China", Strange Parts, January 6, 2020. See position 18': 25". Available at: https://bit.ly/2D5uQ7s

[13] "Here are all the airlines that have banned hoverboards—and why". Splinter News, December 29, 2015. Available at: https://www.dhirubhai.net/redir/general-malware-page?url=https%3A%2F%2Fsplinternews%2ecom%2Fhere-are-all-the-airlines-that-have-banned-hoverboards-1793853771

[14] "E-cigarette exploded in a teenager’s mouth, damaging his jaw". The New York Times, June 19, 2019. Available at: https://www.nytimes.com/2019/06/19/health/ecigarettes-explosion.html

[15] W. Li and Y. Cui - Less fire, more power: without the needlelike growths that can short out cells, lithium-ion batteries will be safer. IEEE Spectrum, vol. 55, no. 9, pp. 44-48, 2018. Available at: https://ieeexplore.ieee.org/document/8449049/

[16] J. Zhang, L. Zhang, F. Sun and Z. Wang - An overview in thermal safety issues of lithium-ion batteries for electric vehicle application. IEEE Spectrum, vol 6, pp. 23.848-23.863, 2018. Available at: https://ieeexplore.ieee.org/document/8353709/

[17] "Tesla investigates video of Model S car exploding". The Guardian, April 22, 2019. Available at: https://www.theguardian.com/technology/2019/apr/22/tesla-investigates-video-of-model-s-car-exploding

[18] "Fitbit recalls 1.7 million ionic smartwatches due to burn hazard". The Consumer Reports, March 2, 2022. Available at: https://www.consumerreports.org/smartwatch/fitbit-recalls-ionic-smartwatches-due-to-burn-hazard-a1122765473/ Accessed on May 9, 2022.

[19] "Why do e-bikes catch fire?". Bycicling, USA, August 23, 2019. Available at: https://www-bicycling-com.cdn.ampproject.org/c/s/www.bicycling.com/bikes-gear/amp28778383/electric-bike-explosion/

[20] "Burning concern: Energy storage industry battles battery fires". S&P Global, May 24, 2019. Available at: https://www.spglobal.com/marketintelligence/en/news-insights/trending/6dfoPLaw67WIEaTV8PSYVQ2

[21] "Lithium-ion battery explodes on Delta aircraft". The Points Guy, March 13, 2018. Available at: https://thepointsguy.com/2018/03/lithium-ion-battery-explodes-on-delta-aircraft/

[22] "Lithium Ion battery explodes in TSA Checkpoint Lane, sends travelers fleeing". The Points Guy, November 13, 2017. Available at: https://thepointsguy.com/2017/11/ion-battery-explodes-tsa-line/

[23] "FAA tells airlines MacBook Pros with defective batteries can’t fly". Ars Technica, August 14, 2019. Available at: https://arstechnica.com/tech-policy/2019/08/faa-bans-some-15-inch-macbook-pros-with-battery-problems-from-flights/

[24] "FAA urges airlines to assess Lithium battery risks". Federal Aviation Administration, USA, February 9, 2016. Available at: https://www.faa.gov/news/updates/?newsId=84785

[25] Rangel Jr., Estellito - Baterias de íons de lítio: incêndios e explos?es. Eletricidade Moderna Magazine, edition 549, December 2019, pp. 42-47. Available at: https://bit.ly/3T96T22

[26] "Regulator says lithium-ion batteries create “unacceptable risks”. PV Magazine, August 8, 2019. Available at: https://pv-magazine-usa.com/2019/08/08/lithium-ion-not-prudent-and-create-unacceptable-risks/

For citing this article:

RANGEL Jr., Estellito. Why do cell phones catch fire and explode? The answers are here! 1ed. Rio de Janeiro, Mar 25, 2019. LinkedIn: @Estellito. Available at: https://lnkd.in/dXZ734z