Just three years ago, science journalist Farhad Manjoo wrote an article for Slate called “Better Batteries Will Save the World.” The subtitle, however, quickly undercut the headline’s claim: “Too bad they’re impossible to make.” This in spite of the recent launch of the Tesla S, the Nissan LEAF, the Chevrolet Volt and the announcement of a slew of new hybrid and pure-electric cars across the automotive spectrum, from econoboxes to two Porsche luxury hybrids.
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The problem Manjoo and others foresaw was several-fold: (1) batteries for cars were too expensive; (2) they seemed to be an unbridgeable distance away from gasoline in terms of “energy density” (the amount of energy contained per weight); and (3) they were possibly dangerous—the emerging key material for batteries, lithium, was unstable by itself, and in air crumbles to a powder. One problem is that humidity can make it explode. Another is that when the stuff is confined it is capable of what is termed “thermal runaway”—rapid heating until it catches fire. So keeping lithium both cool and dry is essential.
But this last caveat is exactly why lithium is attractive as a battery material: its dangerous energy is a great advantage. As a result, there is a quiet lithium rush in battery technology, where real advances have been and will continue to be made. In just a few years, thanks to battery advances, the fossil-fueled car will be an aesthetic choice, not an economic necessity. And our city electric grids will be a lot more complicated yet more predictable, reliable and economical.
Batteries got a lot more efficient when there was a shift from the lead-acid of car batteries and the nickel-cadmium of flashlights to the lithium-ion designs of handheld electronics. Without lithium-ion batteries, we’d almost certainly not be a cell-phone society. But the step up to larger devices such as vehicles and power stations that could save our energy-consumptive life is littered with once-anointed champions—A123 Systems and its sponsor, Fiskar Karma cars; Moli Energy; Avestor; Envia, once slated to power GM’s electric fleet—that all lost millions and barely got out of the starting gate.
If there is anyone who understands the challenges of the battery revolution, it’s the guy who kicked it off by inventing the lithium-ion battery for Exxon, back in the 1970s. M. Stanley Whittingham, now a professor of chemistry at Binghamton University in upstate New York, predicts that “within 10 years, every vehicle will be hybrid or electric.”
He sees lots of reasons to be optimistic. For one, a vast amount of resources are being thrown at the technological challenges of building a better battery, from garage shops and small colleges to well-fed labs at universities like Harvard and Stanford and our major federal laboratories, including Argonne, Lawrence Livermore and Sandia, and on to huge companies in Germany, the Netherlands, France, Japan, Korea and China. No one wants to miss out on the biggest new energy play since oil.
There’s also a clear and urgent need to reduce the greenhouses gases we humans spew. By replacing energy from burning fossil fuels, batteries will make a big difference. And consumers clearly want renewable energy: Electric and hybrid car sales, for instance, are growing robustly.
A better battery offers two big prizes: One is an affordable electric car, the future backbone of our mobile society; the second is a more flexible, dispersed electrical power grid, thanks to advanced stationary batteries that will keep us supplied with electricity at home and work, at lower cost.
End of Range Anxiety
The first electric and hybrid cars were modest proposals, with a range, under electric power, of 40 to 100 miles (excepting the high-priced Tesla, which was rated for 265 miles) but only in ideal conditions. However, the second-generation, due soon, could reach 200 miles. LG Chem, the giant Korean company that supplies the battery packs for both the Chevy Volt and the Ford Focus, reports that its upgraded lithium-ion design will allow these cars a range of 200 miles by 2016. Elon Musk, Tesla’s chairman and leading shareholder, said last August that his company was working on a new battery that would improve the range of its cars up to 500 miles.
At the same time, battery costs are declining. The research firm Navigant notes that five years ago, the price for a laptop battery was about $1,000 per kilowatt-hour; today “that price is closer to $250 per kilowatt-hour.” A July 2012 McKinsey & Company report says that by 2025 the price of the advanced lithium-ion batteries used in cars will drop to $160 per kilowatt-hour—from $500 per kilowatt-hour in 2011. By 2020, Navigant says, batteries will be a $75 billion business, up from $12 billion today.
Sometime in the near future, a battery car will compete in cost with a gasoline-powered car. Musk has said that the Holy Grail is $100 per kilowatt-hour for battery power, which he expects to achieve in “five to seven years.” Tesla, working with Panasonic, is building a $5 billion “gigafactory” in Sparks, Nevada, to manufacture advanced batteries on a scale at which they can be profitable. It is expected to produce 500,000 battery packs a year—doubling the world’s lithium-ion battery output.
Batteries have three basic parts: two electrodes—the anode (negatively charged) and the cathode (positive)—and the bath in between, called the electrolyte (or, in common parlance, the battery fluid), in which ions from the cathode and electrons from the anode swim like fish. What happens there is chemistry. When you close a battery circuit (say, flip on a light switch), the electrons flow out of the anode, through the electrolyte bath, into the cathode, and to the light bulb, where they are used up. Ions flow in the opposite direction. The final result is a neutral state—either a dead or rechargeable battery.
Most new car batteries are rechargeable and use lithium in some form for one of the electrodes, cobalt or carbon for the other, and aluminum oxide for the electrolyte. But researchers thirst for the next big thing—the discovery that would take progress on battery tech from a crawl to a sprint. Several major advances show promise, on the order of three to five times more energy density than lithium-ion. One, the platinum standard, even theoretically surpasses gasoline as fuel for a car.
The most daring concept, lithium-air, reinvents the battery by getting rid of traditional metal for the cathode and replacing it with carbon that pulls oxygen atoms from the air instead of using oxides from the electrolyte. A group at MIT offers a cathode made of nanowire—a structure so minute it is built of single atoms—that is actually made by a genetically altered virus. This is seriously tricky stuff. In the lab, the design proved to have up to three times more capacity and quicker recharging than a typical lithium-ion battery.
As battery chemistry evolves, new materials like these will be critical. Graphene, a super thin (only an atom’s width thick) layer of carbon first produced by two Russian scientists at the University of Manchester in 2003 (and for which a Nobel Prize in physics was granted in 2010), is also being explored as an electrode substance. It is astonishingly strong, flexible and conductive. It can also be made at a mass scale affordably—you can order it online for $5 a gram. In a battery, it could sharply decrease charging time and boost energy storage capacity. Michigan-based XG Sciences and SciNode Systems, out of Northwestern University and Argonne National Laboratory, are both working on graphene batteries. SciNode says it has an anode that can provide three or more times more storage capacity than conventional carbon. Tesla may be also have a graphene initiative, according to China’s Xinhua News Agency.
Another promising variation is a lithium-sulfur design that replaces pricey cobalt with cheap sulfur, and provides much higher energy density. Scientists at Lawrence Berkeley have come up with a design that has double the energy density of a lithium-ion battery and a potential cost as low as $100 per kilowatt-hour. More work needs to be done, but this approach is tantalizingly close to beating gasoline at its own game.
Elsewhere, an iron-phosphate design dispenses with lithium entirely. In China, car manufacturing giant BYD has come out with the e6, an iron-phosphate battery-powered taxi with a range of 185 miles. It’s based on a battery BYD calls the Fe (the element symbol for iron). A BYD car for personal use, the new Qin, is a hybrid with maximum electric-power output of 223 kilowatts, just short of the Tesla S model. After 10,000 charge-discharge cycles, Fe batteries still retain 70 percent of their capacity, say company tests. That’s 27 years of daily recharging.
Get Up, Stand Up
Meanwhile, we may be approaching the golden age of stationary power storage. Batteries that don’t need to move take weight requirements out of the equation, which means developers can use heavier, less exotic and much cheaper materials. Such batteries will make our electric grid more reliable by providing backup power and less costly by harvesting off-peak energy from renewables such as wind turbines and solar arrays to avoid peak-energy cost spikes.
These designs tend to mirror the work being done for cars, with notable exceptions. Aquion, based in Pittsburgh, specializes in microgrids, local complete-power solutions that involve solar or wind or other renewable power generation for remote locations. Its advanced battery costs about the same as an old-fashioned lead-acid battery but lasts twice as long.
And at MIT, Donald Sadoway and his team have developed a long-lasting solid-state battery they say is easily scaled. The materials are common and inexpensive, but the design is entirely innovative: It’s all kept in liquid form, which speeds the exchange of electrons and ions, and the battery maintains itself at high temperature—350 degrees Fahrenheit or more—by means of heavy insulation, yet still produces energy at 75-percent efficiency, more than twice that of an internal combustion engine. It is being made by Cambridge-based Ambri, which says the battery will last decades with little degradation—it projects 10,000 cycles at 98 percent capacity, even at full discharge. That’s huge. Next year, prototypes are headed to four states for field testing.
The trick is to compete with local electric utility rates, and advanced batteries are not quite there yet. But if they just do “peak shaving”—adding extra power to the grid during peak demand times when rates can double or even triple (usually in the late afternoon)—they will pay for themselves quickly.
Of course, there’s a long way to go. As battery pioneer Whittingham says, “We just scratched the surface.” But with the world making every effort to move away from reliance on fossil fuels, there’s no doubt that batteries will play a growing role in our day-to-day lives—and, possibly, help save the planet.
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