38 | New Scientist | 23 January 2021
In June 2020, Yuehe Lin at Washington
State University and his team did just that,
reporting a prototype sodium-ion battery
that had a capacity similar to some lithium-
ion batteries and that could be recharged
more than 1000 times while maintaining
80 per cent of its performance. The crucial
ingredient was a highly concentrated
electrolyte that didn’t lose performance
even if some of it reacted with the electrodes.
Prototypes like this aren’t, of course,
finished products that can be slotted into
a camera or other device. Getting to thatMAGNESIUM
Lithium and sodium are both
good battery ingredients (see
main story). However, their ions
can only carry an electrical charge
of +1. Why not use an ion that
can carry a greater charge – like
magnesium, with its +2 charge?
Several research teams are
working on just this. It is early
days, but magnesium could one
day be the basis of batteries more
powerful and safe than those
made with lithium or sodium.SEAWATER
A major selling point of sodium
batteries is that they can be made
from a plentiful resource, salt.
And what better place to find salt
than in seawater? This is why
Stefano Passerini’s team at the
Karlsruhe Institute of Technologyin Germany has developed a
prototype battery based on
seawater, with the sodium that
is naturally dissolved in it carrying
the charge. Passerini says he
already has keen interest from
investors in South Korea.GLASS BATTERIES
Maria Helena Braga at the
University of Porto in Portugal
has been working on an unusual
battery with John Goodenough,
the Nobel prizewinning inventor
of the lithium-ion battery. The key
component is the electrolyte,
which is made of glass spiked
with sodium ions, which can
travel through it. Every material
needed is easy to source. “It’s the
most eco-friendly cell you can
find,” says Braga. The battery
apparently has extraordinaryproperties: Braga says it can
outperform lithium-based
batteries; the one in her office
has been powering an LED for
five years. Others are having
trouble replicating the device.
Still, with backing from the
likes of Goodenough, this is
one battery to watch.FUEL CELLS
Think of fuel cells as batteries
that you charge by adding fuel
rather than plugging them into
the mains. John Andrews at
RMIT University in Melbourne,
Australia, has developed one that
splits protons from water, which
are then stored inside the battery.
To release this power, oxygen
from air is fed through the
machine, which combines with
the protons to produce waterand electricity. “It’s a very
neat principle,” says Andrews.
“The challenge is to make
it work in a practical device.”LIQUID BATTERIES
Otherwise known as flow
batteries, these work on a similar
principle to regular batteries, but
all the components are dissolved
in liquids. Chemist Lee Cronin at
the University of Glasgow, UK,
and his team have developed
one such battery based on an
enormous tungsten-containing
molecule. The advantage is that
a charged-up liquid battery could
be pumped into a car quickly,
much as petrol is today. The main
barrier at the moment is that
all that electrical charge makes
the liquid electrolyte sticky and
therefore difficult to pump.There isn’t going to be a single type of battery that will address all the world’s energy
storage needs, which is why people have been dreaming up all sorts of variationsBizarre batteries
“ Sodium has the
same chemistry
as lithium, but
none of the
environmental
baggage”
point requires plating the electrodes
onto metals so they connect neatly to
electronic circuits, among other things.
Happily, this stage of development yields
more good news for sodium.
In a lithium-ion battery, the cathode is
plated on to aluminium. But that same
metal can’t be used at the anode because
lithium ions can form an alloy with it, and
so copper is used instead. Unfortunately,
having different metals at each end means
the battery always has an electric potential,
even when not in use. As a result, lithium-ion