Techno Talk
Giant Boost
for Batteries
Mark Nelson
Imagine a battery that you can recharge a thousand-times faster than anything available today. If you
can’t, you should read this article. It covers the intriguing possibility of quantum super-batteries that can
recharge in minutes or even seconds.
W
hen the BBC began to
broadcast 100 years ago, it was
clear that the crude ‘crystal set’
receivers offered for sale were hardly
what you would call a mature technology. Wearing headphones and poking
around to find the most sensitive spot
on the crystal wasn’t a user-friendly
way of listening to the wireless, and it
took a while before valve radios gave us
straightforward tuning and easily adjustable volume controls.
In the same way, it’s hard to deny that
in some ways the rechargeable batteries installed in road vehicles are also
unwieldy and inefficient. Lithium-ion
batteries may be adequate for computers
and smartphones, but when scaled up
for motive power applications, they are
clearly bulky, weighty, slow to recharge
and potentially unsafe. The lithium and
other ‘critical minerals’ used to manufacture them are not only far from plentiful,
but also vulnerable to being weaponised
in global trade wars. What we desperately need is a radically different battery
technology that is easier to make, with
far less ecological impact, faster to recharge and offering much greater energy
density within a given physical volume.
Bring on the super cell!
Does this perfect battery technology
exist? Conceptually it does, and scientists around the world are doing their
utmost to bring it into a state of reality. It goes by the name of the ‘quantum
battery’ and if the term ‘quantum’ is a
word that you recognise but know little about, don’t worry – you’re in good
company. However, so you don’t need
a degree in physics or higher maths to
understand this article – there’s a brief
explainer panel at the end.
So, how do quantum batteries differ
from the batteries used in smartphones
and electric vehicles (EVs)? To quote the
website scitechdaily.com, quantum batteries are a new class of energy storage
devices that operate according to the
principles of quantum physics, the science that studies the atomically small,
where the laws of classical physics do not
always apply. Remarkably, it is possible
8
to create a type of quantum battery in
which the recharge time is related inversely to the amount of stored energy.
A demonstration battery of this kind
has now been built by a team of researchers in Italy led by Tersilla Virgili and
Giulio Cerullo. They write: ‘This leads
to the intriguing idea that the charging
power of quantum batteries is super-extensive, meaning that it increases faster
with battery size. Each molecule represents a unit that can exist in a quantum
superposition state of two energy levels
(fundamental and excited), similar to
the way a qubit, the basic unit of quantum information, can be both 0 and 1
simultaneously in quantum computers.’
Collective behaviour makes for
strength in numbers
Our two experts continue: ‘By constructing the quantum battery in a way that
units can exist in superposition, the
total system can behave collectively.
This behaviour, known as ‘quantum
coherence’, allows the units to act cooperatively [interconnectedly], giving
rise to a hyper-fast charge that depends
on the number of molecule-units. In the
future, this type of device can be applied
in various scientific and technological
fields, such as wireless chargers, solar
cells and cameras.’
This hyper-fast speed points immediately to the killer application of quantum
batteries: the ability to slash the time
taken to recharge the batteries of EVs.
The $64,000 question is, by how much?
Researcher Ju-Yeon Gyhm at the Institute
of Basic Science in the Republic of Korea
has calculated that quantum batteries
could be charged in a thousandth of the
time that classic batteries would take
to be revitalised. What’s more, in normal batteries, the power increases with
the number of cells in parallel. But in
quantum batteries, you can make the
power increase with the square of the
number of cells.
Highly speculative
Rather as Schrödinger’s cat (see below)
can be simultaneously both alive and
dead, the prospect of quantum batteries
becoming viable for practical, commercial application is both real and unreal.
Dr Kavan Modi, associate professor of
quantum physics at Monash University
(Australia) concedes: ‘For us, the theory [is] just an interesting playground to
explore fundamental ideas of time and
energy. I don’t think there will be technological applications. Of course, I may
be completely wrong.’
He may be. If you consider quantum
computers, these were once purely conceptual but are now close to becoming a
commercial reality. Google aims to have
a commercial-grade quantum computer by 2029, and is only one of several
companies racing to build a business
around this emerging technology. In the
same way, the overwhelming economic
necessity to find a means of recharging
EV batteries as rapidly as filling a petrol
tank will incentivise research and development of viable quantum batteries.
At this stage, the only certainty is that
nobody can say whether or when quantum batteries will be commercialised.
But consider LED lighting: electronically generated light was demonstrated as
long ago as 1907 by the English experimenter HJ Round of Marconi laboratories,
using a crystal of silicon carbide and a
cat’s-whisker detector. It took more than
a century to produce affordable LED
lamp bulbs!
Quantum magic
A qubit (short for ‘quantum bit’) is a
basic unit of quantum information,
used in quantum computing. In conventional computing the unit is a bit
(short for binary digit), which can
have only one of two states: one or
zero. But in quantum systems, a qubit
can exist in both states simultaneously, a property that is fundamental to
quantum mechanics (and quantum
computing). The classic example
of this is Schrödinger’s hapless cat,
which hypothetically can be simultaneously both alive and dead, as a
result of its fate being linked to a random subatomic event that may or may
not occur. https://bit.ly/pe-dec22-cat
Practical Electronics | December | 2022
