16 | New Scientist | 29 February 2020
Analysis BatteriesELECTRIC cars are getting cheaper
and their sales are on the rise, but
their future success may depend
on ditching a key ingredient: the
heavy metal cobalt.
The mineral is used in the
lithium-ion batteries that power
most electric cars, and demand for it
is steadily increasing. A new analysis
by Elsa Olivetti at the Massachusetts
Institute of Technology and her
colleagues has found that there
may be cobalt shortages if we don’t
start refining and recycling it more
efficiently or in greater quantities.
They estimate that global demand
for cobalt will rise to between
235,000 and 430,000 tonnes
by 2030 – an amount that is
at least 1.6 times the world’s
current capacity to refine the
metal, as of 2016 figures
(Environmental Science &
Technology, doi.org/dm6b).
About half of all cobalt goes
to make lithium-ion batteries for
electric cars and other consumer
electronics. Demand for these
batteries is projected to more than
quadruple over the next decade.
Cobalt is often produced as
a by-product of copper or nickelmining. It is expensive, at around
$33,000 per tonne, and also
comes with a human cost. Most
of the world’s supply – 60 per
cent – comes from the Democratic
Republic of the Congo, where
mining has been linked to child
labour and deaths.
The new analysis suggests
short-term cobalt supply is
adequate, but that more mining
exploration, such as in the ocean,is required. In addition, we will
need to ramp up cobalt recycling
by recovering it from batteries in
redundant electric cars, laptops
and mobile phones.
Another option is to shift to
batteries that use less cobalt, or none
at all. Elon Musk’s car firm Tesla is in
talks with battery manufacturer CATL
to use entirely cobalt-free batteries
in its China-made cars, according
to a report last week by Reuters.
Lithium-ion batteries in electric
cars commonly use either lithium
nickel cobalt aluminium oxide or
lithium nickel manganese cobaltoxide for their ability to provide a long
lifespan and high energy density – a
key factor in how far an electric car
can go on a single charge.
For short-range cars made
and sold in China, Reuters says
Tesla will instead use lithium iron
phosphate batteries, which are
much cheaper and have less of an
environmental impact compared
with those needing cobalt.
The disadvantage is that they
tend to have a lower energy density,
reducing how far a car can travel
without needing to be charged.
Industry analysts such as Simon
Moores at Benchmark Mineral
Intelligence in London have
suggested that the move is unlikely
to be replicated outside China, saying
it is driven more by a desire to reduce
production costs in China than to
phase out cobalt.
Lithium iron phosphate batteries
are already widely used by other
Chinese firms, including BYD,
the world’s biggest electric car
manufacturer. If other electric
car manufacturers follow
internationally, we may be able
to reduce our dependence on a
dwindling mineral resource. ❚SEBASTIAN MEYER/CORBIS NEWS/GETTY IMAGESNews
Most of the world’s cobalt
is mined in the Democratic
Republic of the Congo“Ants often vomit up food to
feed their co-workers, so
drinking acid helps prevent
diseases spreading”Can electric cars kick the cobalt habit? The mineral is a key component
of batteries used in electric vehicles, but we may run out within a decade.
It would be better to stop using it altogether, says Donna LuEntomologyAcid spray helps
ants keep their
food disease-freeA NUMBER of ant species produce
acid in a poison gland in their
abdomen to spray at enemies.
Now it turns out that they also drink
the acid to kill pathogens in their
food. Because these ants often
vomit up food to feed their
co-workers, this helps prevent
diseases spreading in colonies.
Unlike vertebrates, insects
don’t usually have highly acidic
substances in their stomachs.Simon Tragust at the University
of Bayreuth in Germany and his
colleagues have found that species
such as the Florida carpenter ant
(Camponotus floridanus) increase
the acidity level inside their
stomachs by swallowing acid after
eating. If ants were prevented from
bending round to reach their poison
glands, acidity levels were lower.
Next, the team fed ants food
contaminated with a bacterium that
can cause lethal infections. Ants
that were prevented from drinking
their acid were less likely to survive.
Finally, the team looked at how
likely the disease was to be passedon when ants fed other ants via
regurgitation, as is common in these
species. The poison glands of the
ants being fed were blocked with
superglue. If the glands of the ants
doing the feeding were blocked as
well, more of the ants they fed died.
The results show that drinking
acid plays a major role in protecting
these ants from dangerous microbes
and preventing infections spreading
(bioRxiv, doi.org/dm59).“There is a clear benefit from
this phenomenon,” says Liselotte
Sundström at the University of
Helsinki, Finland, who in 2015
reported that ants self-medicate to
fight off fungal infections. However,
it isn’t clear whether the ants
actively drink from the gland or
whether it happens accidentally as
they groom themselves, she says.
Tragust’s finding isn’t the only
example of ants using acid as
medication. When tawny crazy ants
are sprayed with the venom of fire
ants, they apply acid to their bodies
to detoxify the venom. ❚
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