Now, the hope is that lithium-ion and, later, even more advanced batteries can both make electricity a viable transportation fuel and help fill the gaps in the electrical grid that are currently stifling the implementation of renewable energy sources. Already companies are building tractor-trailer size lithium-ion battery banks and hooking them up to wind and solar farms. The ability to store intermittent sources of energy like these (the sun goes down at night, the wind doesn’t always blow) makes them vastly more practical and affordable as alternatives to polluting sources such as coal.
This is the kind of transformation that the scientists who laid the intellectual foundation for the rechargeable lithium battery had in mind. They were motivated by both scientific curiosity and big-picture social concerns. They began working on the vexing problem of energy storage more than four decades ago, in an age of scarcity and uncertainty much like our own.
2
FALSE START
We have only two modes—complacency and panic.
—James R. Schlesinger, first U.S. secretary of energy
Within four decades of the gas-powered car’s victory over the electric vehicle, air pollution in many world cities had reached life-destroying concentrations. This wasn’t all the automobile’s fault. The clouds of smog that sometimes got trapped in temperature inversions over New York or London and killed anywhere from a few hundred to a few thousand people—smokestacks were largely to blame for those. But cars were a major part of the problem. In Los Angeles, where residents occassionally had to wear gas masks indoors, the automobile was the primary culprit. Unfettered tailpipe emissions reacted with sunlight and transmogrified into a photochemical death cloud that could hang over the city for days or weeks at a time. In 1950, when a Caltech professor identified automotive tailpipe emissions as the main source of smog, there were a half million cars in LA, which is why Los Angeles County’s efforts to crack down on industrial pollution in that decade did approximately nothing to solve the problem. The number of cars continued to grow. By 1966, the 3.75 million cars in Los Angeles County produced 90 percent of the 13,730 tons of air pollution emitted each day. Certain plants—spinach, orchids—could no longer survive in LA. The problem wasn’t confined to Los Angeles, however, nor to just LA and the dense urban belt between Washington, D.C., and New York City. Certain air-quality measurements in Chicago registered high enough concentrations of carbon monoxide to turn a sober driver into a gas-drunk danger. In 1966, a group of orbiting American astronauts tried and failed several times to take a snapshot of their home base in Houston because the city was too obscured by smog.
In 1961, California began requiring that new cars sold in the state come equipped with a system that would send fumes containing unburned fuel back into the engine where they would combust rather than escape through the tailpipe. It didn’t make much of a difference. By January 1967, when Time published a cover story on air pollution called “Menace in the Skies,” a California state public health official told the magazine, “It is clearly evident that between now and 1980 the gasoline-powered engine must be phased out and replaced with an electric-power package.” He clarified: the state needed to “serve legal notice that after 1980 no gasoline-powered motor vehicles will be permitted to operate in California.”
Before long the backlash against the internal combustion engine intensified to a level that is difficult to imagine today. That’s the difference between smog—pollution that hangs in the air, visibly choking American cities—and invisible pollution by carbon dioxide, which will wreak an indeterminate amount of destruction on the planet some decades in the future. When people can’t breathe, they get desperate, and by the time Congress began debating the Clean Air Act of 1970, anti-auto sentiment had grown fierce. In California, one state legislator proposed the outright banning of the internal combustion engine.
By then, the geopolitics of petroleum production had also become nightmarish. Oil-exporting countries had begun rewriting contracts, demanding bigger cuts, raising prices, and in some cases nationalizing the Western oil companies operating on their soil. The dynamic had been building for years, beginning with the 1956 Suez Crisis, in which the Egyptian leader Gamel Abdel Nasser lashed out at his nation’s former occupier, Britain, by seizing control of the narrow waterway through which the majority of its Iranian oil traveled. A more recent memory as the 1970s began would have been 1967’s Six-Day War, when Egypt, Jordan, and Syria tried to destroy Israel with a combination of bullets, bombs, and the “oil weapon.”
Global conflict and pollution aside, Americans were already burning an unsustainable amount of oil. Gasoline shortages began early in 1973, the result of mismanagement rather than international emergency. In April of that year, President Nixon gave the first presidential address on energy. Late that summer, oil began selling for more than the official posted prices. “It was a decisive change, truly underlining the end of the twenty-year surplus,” the oil historian Daniel Yergin wrote.
Then in October 1973, when Egypt and Syria once again attacked Israel and persuaded the oil-exporting countries of the Middle East to levy an oil embargo against the United States, a lifestyle-threatening crisis began. Before the Arab oil embargo, in October, oil was $3 a barrel (in 2010 dollars, about $15). Soon, there simply wasn’t enough to go around. By February of the following year, one-fifth of the gas stations in America would run dry.
When the oil crisis hit, the interest in electric cars that had been revived by the smog plague grew frantic. The problem was that no battery technology could match the versatility and the power of the modern gasoline engine. Electric cars had to compete with sixty years of refinements to the internal combustion engine. Some of the batteries available in the early 1970s could power a small electric car for a minimally acceptable distance, provided the driver never wanted to climb a steep hill or get on the freeway. Some batteries could dump electrons quickly for a sudden boost of power, but then they were all but shot. The available technology would power only the saddest, most anemic electric cars—nothing that would impress the drivers of the day.
At that moment, however, a small international network of scientists was shaking battery science out of a long stagnation by applying the same theories and methods that had yielded the transistor and the integrated circuit. The Stanford University laboratory of Robert Huggins was the seat of this reinvigorated research, and the graduate students and postdocs who passed through it in the late 1960s and early 1970s would go on to reinvent the field.
In 1965, Huggins had gone to the Max Planck Institute in Germany to study with a professor named Carl Wagner—the first scientist to specialize in the movement of ions (charged atoms or molecules) in solids. This sounds like a parody of an overly narrow scientific subspecialty, but in fact it was a rich vein of inquiry. The realization that ions could quickly dart around inside solid materials, almost like atoms floating in a liquid, had enormous implications for battery science. Previously, battery research had assumed that the important reactions inside a battery occurred on the surface of electrodes. Picture a plate of lead dipped in an acidic electrolyte. The reactions that make that battery run happen at the surface where the liquid electrolyte touches the solid plate; the lead inside the plate is just there, adding weight. What if you could engineer reactions that happened inside a solid electrode? That would change things dramatically. And that’s exactly what solid-state ionics, as the study of ion movement in solids is called, did. “If you can store ions inside these materials, rather than just having reactions on the surface, you have the possibility of much greater capacities,” Huggins said. Huggins didn’t have batteries in mind when he went to study with Wagner, but he happened to return to the United States at the moment that battery-powered cars began to seem like the solution to multiple major problems. “I came back with a whole new set of tools, ways of looking at things that I hadn’t had before,” he said. “And not long after I got back here, this announcement came from Ford Motor Company.”
I
n 1967, Neil Weber and Joseph T. Kummer, researchers at Ford’s Dearborn, Michigan, campus, invented a battery that was a radical departure from tradition—the inverse of everything that had come before. Unlike the 12-volt lead-acid starter batteries used in conventional cars, which immerse solid electrodes in a liquid electrolyte, Ford’s new device would do the opposite: the electrodes would be liquid and the electrolyte would be solid. To be more precise, both the positive and negative electrodes (commonly called the cathode and the anode, respectively) would be molten: one made of sulfur, one made of sodium, both heated to 300°C and separated by a solid ceramic electrolyte. In a conference paper, Huggins called it a “revolutionary” approach.
Ford’s unusual electrolyte—the medium that separates the positive and negative electrodes, allowing ions to move between them while preventing the transfer of electrons—fascinated researchers most of all. The cheap, ceramic form of aluminum oxide called beta-alumina had been around for several decades, but until Ford repurposed it as an electrolyte, no one had ever given it much thought. To the human eye, beta-alumina is a glistening white solid, but on a molecular level it’s like a high-rise building with no stairs; sodium ions occupy each floor, but they can enter and exit only through the windows. Putting beta-alumina at the heart of a new type of battery broke a long-standing logjam. “The sodium beta-alumina was a shock to everybody,” Huggins said. “This is so different from all the battery stuff that had been going on for a long time that it was really interesting.”
Researchers in academic and industrial labs around the world turned their attention to beta-alumina, Huggins’s group included. In Huggins’s stable was a young postdoc named Michael Stanley Whittingham. Straight out of a doctoral program at Oxford, Whittingham arrived at Stanford University in 1968, a year after the Ford announcement. At Oxford, he did his master’s thesis on materials called tungsten bronzes, which conducted both ions and electrons and seemed, among other things, like promising catalysts for turning coal to gas. Shortly after his arrival in Palo Alto, Whittingham’s group decided to try to find out exactly how quickly ions could move through Ford’s beta-alumina electrolyte. To do so, they needed to make an electrochemical cell, and in this case that would require a particular kind of electrode material.
Whittingham’s bronzes would work perfectly, because they were insertion compounds, or what in later years would come to be called intercalation compounds. “Intercalation” traditionally refers to the insertion of an extra day into the middle of a calendar—the addition of February 29 to a leap year, for example. In this context, “intercalation” describes a class of crystalline materials that ions can be inserted into without changing their underlying structures. On a molecular level, these bronzes were filled with tunnels, and in the right kinds of chemical reactions, ions can be “inserted” into these tunnels and then yanked out again, repeatedly, without altering the structure of the insertion compound itself. Those experiments were strictly academic, but they were essential for building the knowledge that would soon deliver the world’s first rechargeable lithium battery. “Things were exciting. Things were going on,” Huggins said. “The integration of solid-state electrochemistry into areas of application like batteries and fuel cells—that was brand-new.” The work was fundamental, but the people in Huggins’s lab had idealistic goals. As Michel Armand, one of Huggins’s graduate students from that era, said, “I bought an old car, which was of course a whale on wheels, making something like four miles per gallon in the city. I was from this time convinced that we had to do something with transportation.”
By 1972, enough international scientists were working on solid-state ionics that it was time for a conference. That September, Huggins, Whittingham, Armand, and eighty others gathered in the alpine village of Belgirate, Italy, a hamlet in the mountains north of Milan, where they shared ideas on putting ion transport to use building batteries and fuel cells. Most of the attendees were in their thirties and forties, but there was also an old eminence among them: Carl Wagner. “We were all very pleased he was there,” Huggins said.
Gathered a little more than an hour’s drive from Alessandro Volta’s hometown of Como, the Belgirate delegates talked about every exotic battery chemistry they could imagine in those days: sodium sulfur, lithium sulfur, lithium aluminum iron sulfide, zinc bromine, lithium chlorine. They discussed the feasibility of magnesium oxygen, sodium oxygen, lithium copper fluoride, and zinc silver dioxide. They lusted after the most theoretically promising candidates of all: the “metal-air” batteries—zinc-air, magnesium-air, aluminum-air, sodium-air.
It was a foundational meeting, the beginning of a narrow subsub-discipline that would have an outsize influence on the world. A yellowed black-and-white photo from the conference proceedings shows the group posing before a stand of conifers, a class picture of a scientific community that didn’t yet realize it existed. Today the living members of that delegation are the dons of the academic battery-research scene, the old-timers who after forty often frustrating years have finally seen their work vindicated.
By the time of the Belgirate conference, industrial research into electric drive and advanced batteries was expanding rapidly. In 1972, GM, Ford, Chrysler, and American Motors were all working on electric cars. So was Toyota. So was a coalition of eight German companies that included Daimler-Benz, VW, Bosch, and Siemens. So was Fiat. So were national efforts in Japan, France, and England. As for batteries themselves, in addition to university-based programs, scientists at Argonne National Laboratory, Bell Labs, the Electric Power Research Institute, Dow Chemical, and General Electric were all scouring the periodic table for the solution to the battery problem.
Oil companies were at it too, including the largest of the so-called majors: Exxon. The oil giant believed that in a few decades, most likely after the turn of the millennium, petroleum production would peak, and that the time to diversify was now. They did so by starting a division called Exxon Enterprises, which operated like a venture capital firm. With the backing of the richest industrial company on the planet, Exxon Enterprises attempted to break into businesses as diverse as office equipment, nuclear reactors, and solar panels.
Then as now, Exxon prided itself on being run by engineers, and for the new venture they raided all the best schools, hiring the brightest technical minds they could find and assigning them to basic research that could be applied to any number of new inventions. Michael Stanley Whittingham was one of them.
Just after the Belgirate conference, Exxon Research and Engineering lured Whittingham to the grim industrial corridor of eastern New Jersey. With practically unlimited research funds, his job was to conduct fundamental research on everything energy related except oil. In a small laboratory in Linden, with a refinery staring at them from across Routes 1 and 9, he and his colleagues were to perform the research that would keep Exxon in the black once the pipes across the street were empty.
First, Whittingham and a few colleagues went to work on superconductors, the idea being that if you could find a material that conducted electricity with no resistance at room temperature, then (theoretically) you could dramatically increase the efficiency of any electrical system, not to mention build an entirely new generation of electronics. They started by injecting ions into tantalum disulfide (TaS2), which at the atomic level is like a crystalline sandwich, with an empty spot (called a “galley”) in the middle where ions could go. Sometimes, those ions could make tantalum disulfide do interesting things. Normally the material became a superconductor at 0.8° above absolute zero. With potassium ions inserted into those galleys, however, that temperature increased significantly.
Whittingham began treating various materials with potassium hydroxide, trying to understand why adding potassium ions to tantalum disulfide raised its superconducting temperature. In the process, he noticed that TaS2 injected with potassium had an extremely high “free energy of formation”—that each molecule had a lot of energy tied up in its chemical bonds. Soon he and his colleagues
had an idea: “We said, ‘Hey, we can store energy in this,’”Whittingham said. When Whittingham’s team told their superiors that they might have the raw materials for a new, powerful battery, the managers at Exxon immediately jumped to the idea of an electric car.
Whittingham’s group realized that tantalum was too heavy to go into a battery, so they decided to replace it with the lightest transition metal, titanium. Soon they were experimenting with titanium disulfide (TiS2), another molecular sandwich structure. Paired with the right negative electrode, titanium disulfide could make a battery with a theoretical energy density of up to 480 watt-hours per kilogram, more than twice what was generally accepted as necessary to power a viable electric car. And titanium was an ideal ingredient—it was light, abundant, and an excellent conductor of electricity. They initially tried pairing TiS2 with a negative electrode made of potassium, but potassium was extremely hazardous to handle. Instead, Whittingham turned to lithium.
Whittingham said that lithium came to mind because Japanese fishermen had recently begun using lithium-based primary (nonrechargeable) batteries on fishing floats so they could see their nets at night. Still, the idea of a rechargeable lithium battery had been in the air for a while. It had come up at the Belgirate conference, and Sohio (another oil company), General Motors, and Argonne National Lab were all working on lithium-based batteries around the same time. The difference was that all of those projects involved extremely high temperatures—designs similar to that of Ford’s sodium-sulfur battery, which used molten electrodes and as a result had to be kept impractically hot.
Bottled Lightning Page 3
