“They’ve almost tripled at the cell level since 2010.” That was how Colin McKerracher, head of advanced transport at BloombergNEF, described lithium-ion battery energy densities at the firm’s summit in San Francisco in February 2020. The same cell, in other words, holds close to three times the energy it did a decade earlier.
Why that matters is easy to see on the road. A denser cell lets a carmaker hit a longer range without a bigger, heavier pack. CleanTechnica, reporting on the talk, pointed to the Tesla Model S, which launched with a range of about 250 miles (402 km) per charge. The later Long Range Plus version reached 390 miles (628 km). The Nissan LEAF went from 73 miles (117 km) of range in 2011 to 215 miles (346 km) in 2020.
Weight feeds into price too. A 100 kWh pack gets lighter as density improves, which trims freight and handling costs along the supply chain. McKerracher said battery prices had kept falling in recent years, and BloombergNEF expected a drop from $156/kWh in 2019 to $135/kWh in 2020.
Three chemists, one battery
The cell behind those gains took more than a decade of work by three people. The Royal Swedish Academy of Sciences gave the 2019 Nobel Prize in Chemistry to John B. Goodenough, M. Stanley Whittingham and Akira Yoshino for developing the lithium-ion battery.
Whittingham built the first functional lithium battery in the early 1970s, and it had a nasty flaw. As it was recharged, thin whiskers of lithium grew from the electrode. Once they touched the opposite electrode the battery short-circuited, and it could explode. The Nobel Foundation recounts that the fire brigade had to put out several fires and finally threatened to bill the laboratory for the chemicals used on them.
Goodenough, then a professor of inorganic chemistry at Oxford, reasoned that a metal oxide cathode would give a higher potential than Whittingham’s metal sulphide. His group found it in lithium cobalt oxide. Whittingham’s battery generated more than two volts; Goodenough’s reached four, almost double. He also realised that a battery did not have to be built in its charged state and could be charged afterwards. He published the discovery in 1980.
Yoshino, at Asahi Kasei in Japan, took the next step in 1985. He removed pure lithium from the battery and based it wholly on lithium ions, which are safer. Japanese electronics makers were hungry for lightweight rechargeable cells for video cameras, cordless telephones and computers. Yoshino described his own reading of the market this way: “I just sort of sniffed out the direction that trends were moving. You could say I had a good sense of smell.”
The Nobel committee credits the resulting battery with enabling laptops, mobile phones, electric vehicles and the storage of solar and wind power.
Sources
- The Nobel Prize in Chemistry 2019 – Popular information – NobelPrize.org
- BloombergNEF: Lithium-Ion Battery Cell Densities Have Almost Tripled Since 2010 – CleanTechnica
