Over 18 harrowing days in March, Mark Anthony Conditt deployed at least five battery-triggered pipe bombs across Austin, Texas, killing two and injuring five. On March 20, Conditt blew himself up on the shoulder of Interstate 35 rather than face arrest, grimly concluding the whole horrible episode. As a former materials scientist and chemical engineer whose first job after college was developing experimental lithium-ion batteries, I watched the story unfold with a sort of sick fascination, particularly when NBC News reported that Conditt had used “exotic batteries”—i.e., something akin to the sort of lithium-ion batteries I had been working on. This would later turn out to be incorrect—all six of the battery-trigger mechanisms Conditt devised were made from run-of-the-mill materials, according to the affidavit filed on April 9 in the Western District Court of Texas. But as the energy-rich batteries that I had helped to develop become more common, and more easily accessible, it’s only a matter of time before the next Mark Anthony Conditt starts using them.
“Exotic batteries” are not so exotic these days. The increasingly powerful batteries that power our phones and store the charge from our solar panels may not necessarily be available for purchase at your local convenience store—but they are easy to find nonetheless. For the most part, it’s good that batteries are getting more powerful. Many of the renewable and sustainable energy sources that humanity will need to mitigate climate change, like solar, wind, tidal, and geothermal power, just don’t scale at a moment’s notice to meet peaks in demand. They will absolutely depend on compact, high-capacity batteries to store that energy for later. But what makes these “exotic” batteries better for the environment and increasingly essential for our personal tech is also what makes the prospect of a battery-powered bomb so dangerous.
In a conventional pipe bomb, like the ones law enforcement said Conditt made, a battery serves as nothing more than an electrical fuse, a spark that ignites the other explosive material inside the device. Any old battery can do this, from the tiny lithium-ion coin cell in a Fitbit to the old alkaline AAs that powered my CD Walkman back in high school. But in a bomb powered by an “exotic battery”—a category you can reasonably take to include larger lithium-ion batteries, unusually large batteries in general, or any battery whose internal chemistry is somehow unique (many advanced battery materials are proprietary IP)—the battery itself becomes the explosive, making it far more powerful, and likely far more lethal.
Nearly every variety of lithium-ion battery out there produces phenomenally high blast pressures when it explodes. Two groups that have looked into this, researchers for Underwriters Laboratories and a team from three Taiwanese universities, determined that the force radiating out of a lithium-ion battery explosion is somewhere about 1,580 pounds per square inch. To put that into context, the Centers for Disease Control estimates that prolonged exposure to a blast pressure of simply 20 psi gets you to the point where concrete buildings take damage and human bodies get blown away. Granted, you do not get “prolonged exposure” with a blast from a lithium-ion battery. Most lithium-ion batteries are small, and their 1,580 psi would dissipate more quickly than the 20-psi, gale-force winds blowing out of, say, a coal-mine explosion. But, even if only endured for a little while, 1,580 psi is a terrifying increase in magnitude. (The whole reason that the insurance consultants at Underwriters Laboratories had gotten involved in this, actually, was that routine stress testing for lithium-ion batteries was creating pressure waves that wrecked lab equipment and blew out fume hoods.) In short, if exploding lithium-ion batteries actually had been used inside Conditt’s pipe bombs, we would be talking about many more than two dead and five injured.
As John Cox, an airline-safety consultant with special expertise in lithium-ion batteries, once told Consumer Reports, an exploding lithium-ion battery is “a lot like napalm.” The pressure buildup in the battery typically leads to it flinging out globs of chemicals that are still involved in hot exothermic reactions. Sticky, gooey bits of molten plastic fly out with the debris, slathered in those burning chemicals. Exploding lithium-ion batteries are also unique because they produce two ejection-fire events, a consequence of the fact that the reactions producing all this heat and explosive force are also producing more oxygen, which builds up for another round of combustion.
And of course, the high-tech batteries that could create these explosions are only going to get more powerful. A natural assumption might be that the long arc of battery research bends toward safety, but in reality, developing cheap material with a singularly high chemical potential energy is one of the chief goals of battery research. As one engineer put it to the Financial Times last July, “Lithium ion batteries are so dangerous because they are so energetic. The way you make them more safe is by reducing their propensity to react, which means less performance.”
Even some of the recently touted new avenues toward safer lithium-ion batteries—like the water-based electrolytes coming out of the U.S. Army Research Laboratory—still contain all the materials that a competent amateur could use to make something deadly. (Back when I was conducting lithium-ion research, in fact, most of that electrolyte chemistry had to be done in a humidity-controlled “dry room” simply as a matter of occupational safety.) The dare-to-dream goal in battery tech right now is simply to bring something to market that won’t blow up by mistake when, say, some goofball gently bites down on an iPhone battery at a Taipei electronics store as if it were a suspicious doubloon. (Remember the Samsung Galaxy Note 7, the phone that spent much of 2016 unexpectedly exploding?)
The catch here, unfortunately, is that we desperately need these batteries. Every sector of the economy that has come to depend on customers making payments through a mobile device now depends on lithium-ion batteries. Demand for larger and more potent batteries keeps growing—and frankly, it needs to if we are ever going to reliably harvest and store energy from renewable sources. Right now, any malicious creep who cares to could buy multiple lithium-ion batteries for storing solar power, each one a little bit larger than a box of cereal at Sam’s Club, for just a couple hundred bucks online. (The same goes for lithium-ion batteries made for electric golf carts, bicycles, and even cars.) Anonymous goons like “NurdRage” or “Experimental Fun” are already carefully dismantling these batteries on YouTube just to see the lithium burn. Just last year, both the United States and Great Britain issued brief electronics bans on all incoming flights from several Muslim-majority countries based on intel that al-Qaida in the Arabian Peninsula had planned to sneak bombs on board, inside the battery compartments of laptops. It’s hard to say if those bans were appropriately cautious or completely ridiculous, but clearly there are people in the world thinking about how to use powerful batteries in deadly ways.
The question is what to do about it. One of the battery bomb’s terrorist predecessors, the car bomb, might provide the best clue as to what progress may inevitably look like. After decades of charred bodies and broken buildings, the devastation ultimately spurred not a move away from cars but a third-party fix—a major design shift in the world’s largest cities. Visit the Emirates Stadium in London, the financial district in New York, or the sunken wall around the Washington Monument in D.C., and you’ll notice a subtle siege mentality, thanks to the elegant, pedestrian-friendly, objet d’art barricades erected to stop bomb-laden vehicles—the 6,700-pound bronze NoGo bollards designed by Rogers Marvel Architects; the lush and verdant Tiger Trap esplanades like hidden, corporate moats, devised to support pedestrian foot traffic but also to collapse under the weight of a charging motor vehicle; the turntable security checkpoints that look like sculpture gardens. The exotic-battery bomb will create new versions of these phenomenon too, probably in the form of weird little security choices disguised as aesthetic choices, baked into the next Apple Watch or Tesla Roadster or airport charging station. If we start thinking about all that now, though, perhaps the fix could come before the bloodshed.