Science August 2014 | Page 2

TECHNOLOGY UNCOVERED
Powering gadgets

Alessandro Volta designed the
first modern battery in 1800

alternative ways to
power our gadgets
The batteries that power our technology today are often made from metals and other
substances that are bad for the environment. But greener alternatives are on their way…
Middleton

FIBRES

1. WOOD BATTERIES
Tiny reusable sodium-ion batteries,
1,000 times thinner than a piece of
paper, have been created using wood
fibres by a team of researchers at the
University of Maryland Energy Research
Center, in the US. Wood fibres prove an
easy environment for charged sodium ion
particles to move around in, creating an
electric current.
The wood fibres are coated with
carbon nanotubules, and then packed
into discs of tin. As the wood fibres are
flexible and can wrinkle, this gives
them an advantage over the typical rigid
materials used in other batteries – which
tend to break due to the stresses caused
by expanding and contracting during the
cycles of charging and recharging. This
suppleness means that these wood
batteries can last for more than 400
charging cycles, while current sodium-ion
batteries typically only last for 50 cycles.
The materials used in the battery
are lower cost than lithium, but do not
store energy as efficiently. This may, in
the short-term, make them more
suitable for larger-scale use in places
such as power plants.

ENZYMES

2. THE SUGAR BATTERY
Energy-dense sugar is an excellent
source of fuel for plants and animals,
but until now we’ve struggled to design a
battery that can extract and store its
energy efficiently enough to be viable.
However, researchers at Virginia Tech,
in the US, have developed a sugar-powered
battery that uses specially engineered
enzymes not found in nature to break down
sugar with the same efficiency that the
enzymes inside our own cells do.
The result, the team says, is a biobattery
that holds 10 times the energy of

the lithium-ion batteries commonly found in
your mobile phone. The sugar solution
used is made up of 15% maltodextrin, a
product of corn starch, which slows the
synthetic enzyme. This ensures a steady,
longer-lasting power output.
Another benefit of these batteries is
that they can be recharged simply by
topping up the sugar solution. But the
enzymes involved are temperamental.
Further changes to the enzyme are needed
to ensure the batteries can operate over a
wider range of temperatures.

IMAGE © VIRGINIA TEC /ZHIGUANG ZHU

WORDS BY Jamie