You probably have evidence of a Nobel Prize in your pocket. This year’s Nobel Prize in Chemistry goes to the pioneers of the lithium-ion battery, an invention that has become ubiquitous in the wireless electronics that power modern life: your phone, your laptop and sometimes even your car. Lighter and more compact than the lead and nickel-cadmium batteries of yesteryear, lithium-ion batteries, with further tinkering, could provide a path to storing energy to power homes, airplanes—and even the grid.
The $900,000 prize is split between three scientists: Stanley Whittingham, of Binghamton University in New York, John Goodenough, of the University of Texas in Austin, and Akira Yoshino of Asahi Kasei Corporation in Tokyo. Goodenough, 97, is the oldest-ever recipient of a Nobel Prize.
“This battery has had a dramatic impact on our society,” said Olof Ramström, a chemist at the University of Massachusetts in Lowell, during the announcement of the award.
Like all liquid ion batteries, lithium-ion batteries contain two electrodes—an anode and a cathode—separated by a liquid electrolyte that allows ions to move back and forth. During discharge, stocks of lithium atoms at the anode give up electrons to generate a current for an external circuit. The resulting positively charged lithium ions flow into the electrolyte, while electrons return from their work to the cathode, where they are soaked up, typically by metal oxide materials. The lithium ions sidle up to the metal atoms at the cathode. Charging reverses the flow, pushing the lithium ions to break with the metal atoms and return to the anode.
In the 1970s, Whittingham was one of the first to realize the potential for lithium, an elemental metal that has one “loose” electron in its outermost atomic shell and easily gives it up. But that also makes lithium highly reactive: it will ignite and sometimes explode when exposed even to water in the air. Working at Exxon, Whittingham discovered that titanium disulfide would work well as a cathode: Lithium ions could embed themselves within its layered structure. In 1976, Whittingham demonstrated a working 2.5 volt battery. But as it went through multiple charging cycles, whiskery tendrils, or dendrites, of lithium grew across the electrolyte. When they reached the cathode, the battery short-circuited—sometimes causing fires.
Goodenough, then at the University of Oxford in the United Kingdom, took up the task. He realized that the cathode could soak up more returning electrons if it was made of a metal oxide instead of a metal sulfide. These compounds were also layered and did not significantly expand or contract when taking up or releasing lithium ions. He found that cobalt oxide worked well, and in 1980, published results for a 4 volt battery, nearly twice as powerful as Whittingham’s.
Researchers in Japan were on the lookout for batteries that could power shrinking wireless devices (Sony’s Walkman debuted in 1979). Yoshino made a huge contribution: He found a way to create an anode that was not made of pure lithium, with its susceptibility to growing dendrites. After trying different materials, he found that he could embed the lithium ions within layers of carbon in petroleum coke, an oil industry bioproduct. Yoshino’s battery matched the performance of Goodenough’s but was far safer, and it could survive hundreds of charging cycles. In 1991, a Japanese company began selling the first commercial lithium-ion batteries.
Through the laureates’ work, “We have gained access to a technological revolution: truly portable electronics,” said Sara Snogerup Linse of Lund University in Sweden.
Researchers continue to tinker with the chemical recipes for the anode, cathode, and electrolyte to boost battery power and durability. Today, lithium ions are typically held within an anode framework of graphite, but some researchers are working on anodes made of silicon, which can hold far more lithium ions. Others are studying different cathode materials. Sulfur is promising, because it is cheaper than metal oxides and can hold more electrons—if only researchers can keep the sulfur from reacting with the lithium ions. Lithium-air batteries, which rely on ambient oxygen to oxidize the lithium at the cathode, are thought to be another promising solution.
“It’s not the end of the journey, as lithium is a finite resource and many scientists around the world are building on the foundations laid by these three brilliant chemists,” said Carol Robinson, a chemist at the University of Oxford and president of the Royal Society of Chemistry.
If scientists can find the right balance of capacity, cost, size and weight, some think that these future types of lithium batteries could form the basis of a green electrical grid, providing the energy storage to take up solar and wind energy when those renewable sources are peaking—and unleashing their energy when night falls and winds die down.
Today’s announcement means that all nine laureates in physics, chemistry, and physiology or medicine, this year are male, worsening an already huge gender gap in the world’s most prestigious science awards. Of 616 Nobels awarded since 1901 in the three fields, only 20 (3.25%) have gone to women. (The disparity is even bigger when the laureates’ share of each Nobel is taken into acocunt.) The gap has increasingly come under criticism; a statistical analysis published in May suggested that women lag not because they perform less well but as a result of bias.
This is a developing story.
Source: Science Mag