TheEconomistOctober 12th 2019 811A
lfred nobel’swill states that the an-
nual prizes bearing his name should be
given to those who “have conferred the
greatest benefit to mankind”. The science
awards, though, have a tendency to end up
in the hands of those who have made eso-
teric, if profound, advances rather than
practical ones. Not so with this year’s prize
in chemistry. Three researchers—two from
America and one from Japan—have been
rewarded for their work in developing the
lithium-ion battery.
Lithium-ion batteries have trans-
formed society because they are light-
weight and rechargeable. They have there-
fore become ubiquitous in everything from
mobile phones, tablets and laptops to elec-
tric cars. They could also, in the future, be-
come important in storing the intermit-
tently available energy produced by
renewable sources such as wind and solar
power, as the world attempts to move away
from fossil fuels.
Lithium is the lightest metal in the per-
iodic table (it will float on water, though
not for long, because it is also one of the
most reactive and turns rapidly into lithi-
um hydroxide), and its atoms have three
electrons. Two are tightly bound to its nu-
cleus but the third is easily dislodged to
create a positively charged lithium ion.
The beginnings of making a battery out
of lithium and its ions came in the 1970s,
when the world was gripped by the oil cri-
sis. Exxon, a large oil company, was inter-
ested in developing sources of energy that
did not involve petroleum and one of this
year’s laureates, Stanley Whittingham, was
working at the time in the firm’s research
division. He was investigating potential
superconductors. Specifically, he was in-
terested in solid materials that contained
atom-sized spaces. When ions entered
these spaces—a phenomenon called inter-calation—some of the properties of the sol-
id material, such as its conductivity, would
be changed.
Dr Whittingham discovered that when
lithium ions intercalate with a substance
called titanium disulphide, the interaction
stores a useful amount of energy. Employ-
ing metallic lithium as an anode and titani-
um disulphide as a cathode, he built a re-
chargeable battery cell that worked at room
temperature. In it, lithium at the anode is
ionised and the ions thus produced then
move through an intervening electrolyte
and into the spaces in the titanium disul-
phide cathode. The liberated electrons,
meanwhile, traverse an external circuit to
create an electric current that can be used
to do work. During its recharge cycle, the
external current is reversed and the lithi-
um ions move back through the electrolyte
in response (see diagram 1, overleaf ).
At first Exxon thought the battery had
great potential and decided to commercial-
ise it. But when oil prices fell back the com-
pany lost interest. It was about then that
the second of this year’s chemistry laure-
ates, John Goodenough, who was working
at Oxford University, came across the idea
and decided to try to improve it. In 1980 he
found that, by replacing the titanium dis-
ulphide in the cathode with cobalt oxide,
he could double the output voltage.
Akira Yoshino, the third laureate, took
Dr Goodenough’s idea and transformed it
into the modern battery that sits inside theThe 2019 Nobel prizes
Supercharged!
Batteries, exoplanets, cosmology and cell biology all win Nobel laurels
Science & technology
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