Science-Watching: Why Do Batteries Sometimes Catch Fire and Explode?

[from Berkeley Lab News, by Theresa Duque]

Key Takeaways
  • Scientists have gained new insight into why thermal runaway, while rare, could cause a resting battery to overheat and catch fire.
  • In order to better understand how a resting battery might undergo thermal runaway after fast charging, scientists are using a technique called “operando X-ray microtomography” to measure changes in the state of charge at the particle level inside a lithium-ion battery after it’s been charged.
  • Their work shows for the first time that it is possible to directly measure current inside a resting battery even when the external current measurement is zero.
  • Much more work is needed before the findings can be used to develop improved safety protocols.

How likely would an electric vehicle battery self-combust and explode? The chances of that happening are actually pretty slim: Some analysts say that gasoline vehicles are nearly 30 times more likely to catch fire than electric vehicles. But recent news of EVs catching fire while parked have left many consumers – and researchers – scratching their heads over how these rare events could possibly happen.

Researchers have long known that high electric currents can lead to “thermal runaway” – a chain reaction that can cause a battery to overheat, catch fire, and explode. But without a reliable method to measure currents inside a resting battery, it has not been clear why some batteries go into thermal runaway, even when an EV is parked.

Now, by using an imaging technique called “operando X-ray microtomography,” scientists at Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley have shown that the presence of large local currents inside batteries at rest after fast charging could be one of the causes behind thermal runaway. Their findings were reported in the journal ACS Nano.

“We are the first to capture real-time 3D images that measure changes in the state of charge at the particle level inside a lithium-ion battery after it’s been charged,” said Nitash P. Balsara, the senior author on the study. Balsara is a faculty senior scientist in Berkeley Lab’s Materials Sciences Division and a UC Berkeley professor of chemical and biomolecular engineering.

“What’s exciting about this work is that Nitash Balsara’s group isn’t just looking at images – They’re using the images to determine how batteries work and change in a time-dependent way. This study is a culmination of many years of work,” said co-author Dilworth Y. Parkinson, staff scientist and deputy for photon science operations at Berkeley Lab’s Advanced Light Source (ALS).

The team is also the first to measure ionic currents at the particle level inside the battery electrode.

3D microtomography experiments at the Advanced Light Source enabled researchers to pinpoint which particles generated current densities as high as 25 milliamps per centimeter squared inside a resting battery after fast charging. In comparison, the current density required to charge the test battery in 10 minutes was 18 milliamps per centimeter squared. (Credit: Nitash Balsara and Alec S. Ho/Berkeley Lab. Courtesy of ACS Nano)
Measuring a battery’s internal currents

In a lithium-ion battery, the anode component of the electrode is mostly made of graphite. When a healthy battery is charged slowly, lithium ions weave themselves between the layers of graphite sheets in the electrode. In contrast, when the battery is charged rapidly, the lithium ions have a tendency to deposit on the surface of the graphite particles in the form of lithium metal.

“What happens after fast charging when the battery is at rest is a little mysterious,” Balsara said. But the method used for the new study revealed important clues.

Experiments led by first author Alec S. Ho at the ALS show that when graphite is “fully lithiated” or fully charged, it expands a tiny bit, about a 10% change in volume – and that current in the battery at the particle level could be determined by tracking the local lithiation in the electrode. (Ho recently completed his Ph.D. in the Balsara group at UC Berkeley.)

A conventional voltmeter would tell you that when a battery is turned off, and disconnected from both the charging station and the electric motor, the overall current in the battery is zero.

But in the new study, the research team found that after charging the battery in 10 minutes, the local currents in a battery at rest (or currents inside the battery at the particle level) were surprisingly large. Parkinson’s 3D microtomography instrument at the ALS enabled the researchers to pinpoint which particles inside the battery were the “outliers” generating alarming current densities as high as 25 milliamps per centimeter squared. In comparison, the current density required to charge the battery in 10 minutes was 18 milliamps per centimeter squared.

The researchers also learned that the measured internal currents decreased substantially in about 20 minutes. Much more work is needed before their approach can be used to develop improved safety protocols.

Researchers from Argonne National Laboratory also contributed to the work.

The Advanced Light Source is a DOE Office of Science user facility at Berkeley Lab.

The work was supported by the Department of Energy’s Office of Science and Office of Energy Efficiency and Renewable Energy. Additional funding was provided by the National Science Foundation.

The Levinas Facial Theme in Novels

[a continuation of Education and Spontaneous Learning]

The Face of Another (Japanese: 他人の顔, HepburnTanin no kao) is a 1964 novel written by the Japanese novelist Kōbō Abe. Like other stories written by this author, the novel explores the alienation of modern man from urban society.[1] It is written in the first person narrative mode, and is divided into a prologue, three “notebooks” (black, gray, and white), and a concluding letter from the protagonist’s wife.[2] In 1966, it was adapted into a film directed by Hiroshi Teshigahara.[3]

An industrial accident has severely burned the face of an unnamed plastics scientist. His wife is repulsed by his disfigurement and refuses to have sexual contact with him. To regain the affection of his wife, he attempts to create a prosthetic mask in a rented apartment. With this new “face,” the protagonist sees the world in a new way and begins a clandestine affair with his estranged wife. Although the mask gives the man newfound freedom, at the end of the story, it becomes difficult to determine if the mask has taken ownership of the man or the man has taken ownership of the face.[1][2][4]

There is also a subplot following a hibakusha woman who has suffered burns to the right side of her face. In the novel, the protagonist sees this character in a film; in the film version, this is deliberately obscured.

References
  1. Hoover, William (2019). Historical Dictionary of Postwar Japan, 2nd edition. Lanham, MD: Rowman & Littlefield. p. 11. ISBN 9781538111550.
  2. Abe, Kobo (1980). The face of another. Internet Archive. New York: Perigee Books. ISBN 978-0-399-50484-6.
  3. Teshigahara, Hiroshi (1967-06-09), Tanin no kao (Drama, Horror, Sci-Fi), Teshigahara Productions, Tokyo Eiga Co. Ltd.
  4. Rush, Zachariah (2014). Beyond the Screenplay: A Dialectical Approach to Dramaturgy. Jefferson, NC: McFarland. p. 59. ISBN 9780786466030
See Also

La Belle Image by Marcel Aymé, a novel with a similar premise.

Education and Finality Claims

Stephen Hawking kept saying he wanted to discover the ultimate world-equation. This would be the final “triumph of the rational human mind.”

This would presumably imply that if one had such a world-equation, one could infer or deduce all the formalisms in a university physics book with its thousand pages of equations, puzzles and conundrums, footnotes and names and dates.

While hypothetically imaginable, this seems very unlikely because too many phenomena are included, too many topics, too many rules and laws.

There’s another deep problem with such Hawking-type “final equation” quests. Think of the fact that a Henri Poincaré (died in 1912) suddenly appears and writes hundreds of excellent science papers. Think of Paul Erdős (died in 1996) and his hundreds of number theory papers. Since the appearance of such geniuses and powerhouses is not knowable in advance, the production of new knowledge is unpredictable and would “overwhelm” any move towards some world-equation which was formulated without the new knowledge since it was not known at the time that the world-equation was formalized.

Furthermore, if the universe is mathematical as MIT’s Professor Max Tegmark claims, then a Hawking-type “world-equation” would cover all mathematics without which parts of Tegmark’s universe would be “unaccounted for.”

In other words, history and the historical experience, cast doubt on the Stephen Hawking “finality” project. It’s not just that parts of physics don’t fit together. (General relativity and quantum mechanics, gravity and the other three fundamental forces.) Finality would also imply that there would be no new Stephen Hawking who would refute the world-equation as it stands at a certain point in time. In other words, if you choose, as scientists like Freeman Dyson claim that the universe is a “vast evolutionary” process, then the mathematical thinking about it is also evolving or co-evolving and there’s no end.

There are no final works in poetry, novels, jokes, language, movies or songs and there’s perhaps also no end to science.

Thus a Hawking-type quest for the final world-equation seems enchanting but quixotic.

Meaningfulness versus Informativeness

The Decoding Reality book is a classic contemporary analysis of the foundations of physics and the implications for the human world. The scientists don’t see that physics and science are the infrastructure on which the human “quest for meaning” takes place. Ortega (Ortega y Gasset, died in 1955) tells us that a person is “a point of view directed at the universe.” This level of meaning cannot be reduced to bits or qubits or electrons since man is a “linguistic creature” who invents fictional stories to explain “things” that are not things.

The following dialog between Paul Davies (the outstanding science writer) and Vlatko Vedral (the distinguished physicist) gropes along on these issues: the difference between science as one kind of story and the human interpretation of life and self expressed in “tales” and parables, fictions and beliefs:

Davies: “When humans communicate, a certain quantity of information passes between them. But that information differs from the bits (or qubits) physicists normally consider, inasmuch as it possesses meaning. We may be able to quantify the information exchanged, but meaning is a qualitative property—a value—and therefore hard, maybe impossible, to capture mathematically. Nevertheless the concept of meaning obviously has, well… meaning. Will we ever have a credible physical theory of ‘meaningful information,’ or is ‘meaning’ simply outside the scope of physical science?”

Vedral: “This is a really difficult one. The success of Shannon’s formulation of ‘information’ lies precisely in the fact that he stripped it of all “meaning” and reduced it only to the notion of probability. Once we are able to estimate the probability for something to occur, we can immediately talk about its information content. But this sole dependence on probability could also be thought of as the main limitation of Shannon’s information theory (as you imply in your question). One could, for instance, argue that the DNA has the same information content inside as well as outside of a biological cell. However, it is really only when it has access to the cell’s machinery that it starts to serve its main biological purpose (i.e., it starts to make sense). Expressing this in your own words, the DNA has a meaning only within the context of a biological cell. The meaning of meaning is therefore obviously important. Though there has been some work on the theory of meaning, I have not really seen anything convincing yet. Intuitively we need some kind of a ‘relative information’ concept, information that is not only dependent on the probability, but also on its context, but I am afraid that we still do not have this.”

For a physicist, all the world is information. The universe and its workings are the ebb and flow of information. We are all transient patterns of information, passing on the recipe for our basic forms to future generations using a four-letter digital code called DNA.

See Decoding Reality.

In this engaging and mind-stretching account, Vlatko Vedral considers some of the deepest questions about the universe and considers the implications of interpreting it in terms of information. He explains the nature of information, the idea of entropy, and the roots of this thinking in thermodynamics. He describes the bizarre effects of quantum behavior—effects such as “entanglement,” which Einstein called “spooky action at a distance” and explores cutting edge work on the harnessing quantum effects in hyper-fast quantum computers, and how recent evidence suggests that the weirdness of the quantum world, once thought limited to the tiniest scales, may reach into the macro world.

Vedral finishes by considering the answer to the ultimate question: Where did all of the information in the universe come from? The answers he considers are exhilarating, drawing upon the work of distinguished physicist John Wheeler. The ideas challenge our concept of the nature of particles, of time, of determinism, and of reality itself.

Science is an “ontic” quest. Human life is an “ontological” quest. They are a “twisted pair” where each strand must be seen clearly and not confused. The content of your telephone conversation with your friend, say. is not reducible to the workings of a phone or the subtle electrical engineering and physics involved. A musical symphony is not just “an acoustical blast.”

The “meaning of meaning” is evocative and not logically expressible. There’s a “spooky action at a distance” between these levels of meaning versus information but they are different “realms” or “domains.”

Education and Intuition

The 2014 PBS TV series, How We Got to Now is a good miniseries on improvements in glass-making, sewage, water management, etc. that serve as the material/organizational basis for this modern world.

At one point in the series, the host Steven Johnson, a kind of historian of innovation, reveals his idea of how innovation occurs and he focuses on mavericks whose breakthrough is not a sudden “Eureka!” moment, but rather what Johnson calls “a slow hunch.” In other words, the innovators struggle along with a partially understood sense of possibility, very inchoate in the beginning, that comes into better focus with the passage of years and decades, via missteps and boondoggles.

The science writer Arthur Koestler shines a different “flashlight” on this problem of intuitive creativity and its bearing fruit:

Arthur Koestler, CBE (UK: 5 September 1905 – 1 March 1983) was a Hungarian British author and journalist. Koestler was born in Budapest. His masterful book, The Sleepwalkers, is a kind of defense of the way people in the past benefited from a productive sleepwalking on their journeys to scientific advance.

The Sleepwalkers: A History of Man’s Changing Vision of the Universe is a 1959 book by Arthur Koestler. It traces the history of Western cosmology from ancient Mesopotamia to Isaac Newton. He suggests that discoveries in science arise through a process akin to sleepwalking. Not that they arise by chance, but rather that scientists are neither fully aware of what guides their research, nor are they fully aware of the implications of what they discover.

A central theme of the book is the changing relationship between faith and reason. Koestler explores how these seemingly contradictory threads existed harmoniously in many of the greatest intellectuals of the West. He illustrates that while the two are estranged today, in the past the most ground-breaking thinkers were often very spiritual.

Another recurrent theme of this book is the breaking of paradigms in order to create new ones. People—scientists included—hold on to cherished old beliefs with such love and attachment that they refuse to see the wrong in their ideas and the truth in the ideas that are to replace them.

The conclusion he puts forward at the end of the book is that modern science is trying too hard to be rational. Scientists have been at their best when they allowed themselves to behave as “sleepwalkers,” instead of trying too earnestly to ratiocinate.

Add to this overview the “creativity” discussion on The Charlie Rose Show in The Brain Series (2010), where Professor Eric Kandel, the Nobel-prize physiologist, states forthrightly that brain research has no idea about creativity and the prospect of explaining creativity in terms of the brain is very distant indeed.

The arrival of a “slow hunch” (Steven Johnson) and “productive sleepwalking,” as opposed to unproductive kinds of woolgathering (Arthur Koestler), are mind, personality and spirit issues, although they do have brain-chemical “correlations” that cannot be explained mechanistically.

Mysteries all have physical/chemical “correlations” but cannot be simplistically reduced to biochem or genomics.