Changing the Battery
By Michael Abrams
Have you seen flamingos on the moon? In marshes, swamps, and zoos, the tall birds are already striking enough—fire-feathered, boomerang-beaked, and perched on a single, knobby-kneed stick of a leg. But put them on an endless bleached and flat landscape, and they become otherworldly.
Bolivia’s Salar de Uyuni is just such a landscape. The largest salt flat in the world, it stretches for thousands of miles and is famously easy to spot from space. In the rainy season, a thin layer of water turns the remote, 12,000-foot-high plain into the world’s largest mirror, reflecting the sky as well as adventurous tourists—and thousands of flamingos that gather there each year to lay their eggs. It’s the only spot on the planet where all three species of volcano flamingos breed. “Just imagine thousands of flamingos breeding together, in one place, once a year,” says Marita Davison, a researcher at Cornell’s Department of Ecology & Evolutionary Biology. “They are basically putting all their eggs in one basket, in one lake.”
That’s precarious enough, even if the lake remained untouched. But that may not be in the cards—because the flamingos are literally standing on our batteries. If you dig just a few feet beneath the Salar de Uyuni, mix the earth with some water, and let it evaporate, in a couple of years you’ll be left with a pile of lithium crystals—the very stuff that powers your phone, your laptop, and other assorted portabilia. It may even power your next car, if it’s an electric one. Indeed, we owe the very mobility of our mobile gadgets to this third element on the periodic table.
Worldwide demand for the metal is sure to increase in the coming years—to unprecedented levels if electric cars line our roadways. Some experts predict that current suppliers of lithium could deplete known deposits and stores within a few decades. And if the world turns to Bolivia’s salt flats for its lithium fix, Bolivia’s flamingo rookery could be in trouble.
But the potential lithium shortage has also spurred interest in finding alternatives that could take the pressure off lithium-laden ecosystems. Scores of energy researchers are trying to build better batteries that use less lithium to store more electricity. Many are hoping to tap new materials—polymers, nanotubes, carbon fibers, and even algae—to create a better storage device. Lithium-air batteries are likely to increase the power of the battery by many multiples. But the most far-sighted view is that the future of the battery may in fact involve no battery at all.
The battery is due for an overhaul—the technology hasn’t changed much in the past 200, or possibly 2,000, years. In essence, all batteries consist of three elements: an anode and a cathode (the electrodes), plus an electrolyte. The anode and cathode are two elements with differing electrochemical potential: the cathode (the negative end of the battery) is designed to give off electrons and the anode (the positive end) to absorb them. The two are separated by or submerged in an electrolyte, a conductive substance ready to react with the electrodes. When a circuit is created with all three, electrons will flow from the anode through the electrolyte to the electrode, creating energy.
Odd, grenade-shaped vessels found in Iraq and dating to the time of Christ have all the elements of the cartridges we carry in our electronics today. Their electrolyte was probably wine, and re-creations of the “Baghdad batteries” using this liquid have, in fact, produced voltage. Over the centuries, the battery’s basic equation has stayed the same. What’s changed is the material that makes up the electrodes and electrolytes.
When Alessandro Volta, official inventor of the battery, first started tinkering, he used a pair of dead frog legs as an electrolyte. In the late 1700s, physician Luigi Galvani had found that such legs, hanging from a metal hook, would twitch when he touched a nerve with a scalpel, but he attributed the contraction to “animal magnetism.” Volta proved that the kick came from the reaction between the metals in the hook and scalpel. In 1800, he replaced amphibian limbs with brine-soaked cardboard and the hook and scalpel with copper and zinc, thus inventing the voltaic pile.
Over the next 200 years, new materials made batteries more efficient and more portable—albeit at a painfully slow pace. Battery performance has improved only about eightfold in the past 150 years. (Compare that to processing power: today’s iPhone is 100 times faster than the unwieldy portable computers of just 30 years ago).
Soon after the voltaic pile arrived on the scene, batteries were no longer just items for experimentation. Their debut on a mass scale was intended to help power telegraph networks—but there were some side effects. The Grove cell, for instance, had the unfortunate tendency to discharge poisonous gases. Its voltage decreased with age; when discharged, its life was over.
Rechargeability came in 1859, with the lead-acid battery—the same configuration that starts our combustion engine–powered autos today. Put a charge into one, and the electrons head back to the lead anode, repowering the battery and allowing the radio to stay on when the ignition is off. Yet lead-acid batteries have the distinct disadvantage of being heavy as hell.
True portability didn’t arrive until dry-cell batteries hit the market in 1887. The first patented one had a plaster-of-Paris electrolyte (mixed with ammonium chloride), a package not unlike that of the Duracell™ batteries that still power our flashlights.
Nickel-cadmium and alkaline increased voltage and capacity in the early twentieth century, but there were no leaps or bounds in the power-to-weight ratio until the advent of the lithium-ion battery. Turning lithium into an electrolyte was no small feat. The very reactive nature that gives lithium its power also makes it highly flammable and corrosive. Working for Sony in the 1980s, the Dickensian-named John B. Goodenough managed to tame the element and turn it into a commercial battery. Today’s lithium-ion battery is a good eight times lighter than the nearest competitor, and laptop-battery explosions are few and far between.
The advantages of lithium-ion batteries are rarely disputed. They store more energy per pound than any other commercial battery and have a slow “self-discharge rate.” (That is, they keep their charge when not being used). Lithium is easy to mine and relatively safe if tossed into the landfill.
Its lightness, power, and ease of exploitation are key to producing electric cars that can accelerate quickly and cover hundreds of miles without a fuel stop. Until the advent of lithium, the electric car was imagined only as a short-range vehicle. The General Motors EV1, introduced in 1996, needed to be recharged after 75 miles. Today’s Tesla Roadster, an electric sports car, can go for some 250 miles before recharging. At present, fully electric vehicles on U.S. roads number in the thousands. President Barack Obama hopes to increase that number to 1 million by 2015. And if technology, policy, and demand pave the way, it’s not unlikely that 100 million vehicles a year will depend on lithium in a few decades.
That spike in demand may mean that in 10 to 30 years, we will cease to meet our lithium needs as cheaply as we do now. Ecologist Thomas Cherico Wanger, a post-doc at Stanford, warns that “total global lithium resources are likely to be depleted before 2025.” (1) Other predictions are less dire but still point to a dip in supply. But Brian Jaskula, a lithium specialist for the U.S. Geological Survey, says that lithium is not likely to be used up. Many new sources are appearing in the U.S., Argentina, and elsewhere. Lithium is also easy to recycle and, if demand is high enough, can be extracted from seawater. Even so, if the electric car does take off, “there may be some short-term disruptions in supply between 2020 and 2030,” says Jaskula. And that is when Bolivia’s remote salt flats are likely to be tapped.
Regardless of the amount of lithium out there to exploit, most battery researchers and other experts agree that eventually it will be replaced by something else—most likely something as yet unimagined. If indeed our use of lithium for energy storage is a temporary one, it seems all the more foolish and tragic to wreck a unique ecology.
So, can we build a greener battery without lithium? The vast majority of researchers are focusing on creating more-efficient electrodes and reducing “ungreen” metals in our current batteries. But one of the most ambitious ideas of all is rethinking the very notion of what a battery is. Researchers at Imperial College, London, and SUNY Buffalo are envisioning a future in which ordinary objects—concrete, plastics, carbon fiber—in the body of cars and in buildings hold the energy we need to run them.
“Right now, the casing to your computer or mobile phone has only a structural purpose—so you can throw it around and pick it up again,” says Joachim Steinke, a leader in polymer chemistry at Imperial College. The protective shells of our gadgets, and particularly of our vehicles, add considerable weight and little else. But new carbon-fiber weaves produced by Steinke and the Structural Energy Storage Team at Imperial could mean that this dumb weight could turn a lot less dumb.
Steinke and his team hope to give a second purpose to the supporting structure of our electronics and cars. The carbon fiber they envision—they’ve already created a small swatch of it—would work as a capacitor (actually, a supercapacitor). Rather than storing energy electrochemically as a battery does, a capacitor stores it electrostatically. Positive and negative charges are separated, creating the potential for electricity when they are united. Because capacitors can dump their entire charge at once, they work well for devices that need a surge of energy, such as an accelerating car.
The Imperial College team is now working with Volvo to replace a small piece of a car’s floor with their carbon fiber to help power it. But in Steinke’s vision of the future, the entire body of the car would hold a charge, allowing the battery to shrink, if not disappear entirely. The Tesla Roadster weighs about 1,250 kilograms—500 of which are the battery. “So if we could reduce the weight of the batteries by just a factor of two, says Steinke, “that would make the Roadster much more efficient.”
In the greenest of worlds, after you’ve parked your Roadster in the garage and plugged it into a socket to charge for the night, the energy would come from the sun, the wind, or another renewable source. But even then, there’s still the problem of energy storage—the sun doesn’t shine at night, and the wind doesn’t blow 24 hours a day. Right now, the solution is to stash the day’s rays in a battery of batteries in the basement. But if materials scientist Deborah Chung of SUNY Buffalo has her way, we may be able to turn the very structure of our homes into batteries. She’s working on a technology for which plugging into the wall will mean plugging into the wall. “Everybody’s just looking at little batteries,” says Chung. “That’s wonderful, that’s great. But it would be good if people could jump out of that box and look even further. If structures can store energy, it really opens the horizon a lot. Concrete structures are all over the place.”
Concrete is a porous material made with a mix of water and cement—and water works as an electrolyte, albeit not a very efficient one. When Chung slapped an anode and an electrode onto a concrete slab, she managed to produce a few microwatts per hour per kilogram. That’s enough to power a hearing aid or two. “What I have established is basic scientific feasibility,” says Chung. “A lot more research needs to be done to get the energy density up to speed and to get it to be rechargeable.” To do that, someone needs to find the right ratio of water to cement and try different materials for the electrodes. The cement could also be spiked with conductive materials to hold a bigger charge, but doing so would introduce a risk of corrosion. Treated or not, rechargeable cinder blocks are more likely to be the bank rather than to break it. “It’s dirt cheap, however you look at it,” says Chung.
In a world gone wireless, it seems downright antiquarian to plug something as technologically advanced as an electric car into a wall with a cord. But researchers at Utah State University’s Energy Dynamics Laboratory say we won’t have to. They’ve developed the prototype for a wireless energy system that would pump electricity into cars while they drive. Their solution could ultimately solve the car-battery problem by taking the power out of the car altogether.
The trick relies on magnetic-resonance coupling. In essence, a large coil under the road would switch on as a car nears it, creating a magnetic field. That field would be shaped and tuned to a specific frequency, allowing the electricity to be transmitted to a receiving coil on the bottom of the car. “Tesla had the idea of wireless power 100 years ago,” notes Jeff Muhs, the lab’s director. “About four years ago, it became technically feasible.
At least initially, the battery would still be an essential element. As the population of electric cars expands in the coming years, Muhs’s coils could be buried beneath parking lots, garage floors, and wireless “filling stations.” Later, they could be embedded in roadways. “Assuming that you are within 20 miles of one of these roadways, it would be possible to reduce the battery size to 20 percent of the battery we need now,” says Muhs.
Eventually, though, if wireless power transfer technology proves to be the answer, every highway, side road, back alley, and driveway would be outfitted to pulse power into the fully electric vehicles that slide over them. “Thirty or 40 years down the road, you’d have this fully integrated into the system,” says Muhs. “You’d see every state in America have a lane—maybe the ‘easy charge lane’—and we would be tuning our system to continue to grow the electric roadway grid, much as we did the interstate highway system 50 or 60 year ago.”
If that sounds impossible, Muhs suggests taking a look at the lighting industry. “One-hundred thirty years ago, you used to lug lamp oil around. What happened was, we automated the use of electricity. Took the users out of the loop, eliminated the need for on-site storage, transformed the industry. The next logical step would be electric roadways.”
Right now, though, the prototypes for wireless power transfer, carbon-fiber composites, and similar futura could fit into the trunk of a Prius. Until they get off the ground and on the road, we’ll be dependent on lithium. And the flamingos, serenely balanced on one leg, may have to do their standing elsewhere. ❧
–Michael Abrams is a freelance writer based in New York who used at least four lithium-ion batteries while writing “Changing the Battery.” He is the author of Birdmen, Batmen, and Skyflyers: Wingsuits and the Pioneers Who Flew in Them, Fell in Them, and Perfected Them, has written for Discover, Wired, and Men’s Health and is a regular contributor to ASME.com. He also plays a mean banjo.
1. Wanger. T.C. 2011. The lithium future—resources, recycling, and the environment. Conservation Letters doi:10.1111/j.1755-263X.2011.00166.x.