Cobra Effect · Everyday machines
How a battery learned to carry lithium safely
How three scientists made a rechargeable battery that carries lithium safely.
7 cards, read aloud in 2:47, with a test and sources.
In the 1970s, an oil crisis pushed companies to look for better ways to store energy.
At the oil company Exxon, Stanley Whittingham found a material that could store lithium ions in the gaps between its layers. His rechargeable battery gave more than two volts. But its anode was lithium metal, which grew thin spikes as it charged, and could short circuit and catch fire.
Around 1980, John Goodenough found a way to get a higher voltage.
He reasoned that a metal oxide would work better than the sulphide Whittingham had used. His team at Oxford found that lithium cobalt oxide gave about four volts. Oxford did not patent it, and Goodenough received no royalties.
In 1985, Akira Yoshino at Asahi Kasei built a version safe enough to use.
He paired Goodenough’s cathode with a carbon anode that could also hold lithium ions. His battery contained no lithium metal at all, only lithium ions. In a safety test, he dropped a lump of iron onto a cell, and nothing happened.
Inside the battery, lithium ions shuttle back and forth.
When it powers a device, ions travel through the liquid inside, from the carbon side to the metal oxide side. Electrons cannot pass through that liquid, so they flow round the outside circuit instead, doing useful work. Charging pushes both back again. Because the ions slot in and out without wrecking the materials, the battery survives hundreds of charges.
In 1991, Sony began selling the first lithium ion batteries.
They were light, and held a lot of energy for their size. They helped make portable electronics far more practical. Today they power phones, laptops and electric cars.
In 2019, Goodenough, Whittingham and Yoshino shared the Nobel Prize in Chemistry.
Goodenough was ninety seven, the oldest person ever awarded a Nobel Prize. He died in 2023, aged a hundred. Each of the three had solved a different part of the problem.
So when an invention seems to belong to one person, ask who solved each piece of it.
Whittingham showed that lithium ions could shuttle in and out of a material. Goodenough found a cathode with a much higher voltage. Yoshino removed the dangerous metal, and made a battery safe to sell.
Sources
- They developed the world’s most powerful battery, The Nobel Prize. The popular background to the 2019 prize, including the drop test.
- How do lithium ion batteries work?, Explain that Stuff. A plain explanation of ions shuttling between the electrodes.
- Lithium ion battery, Wikipedia. The history from Whittingham to Sony, and how the cells work.
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