(MUSIC PLAYS)
SPEAKER: The world right now is at a stage where we are embracing renewable
energy solutions and moving away from fossil fuels.
This is especially true with the adoption of electric vehicles,
with the use of fossil fuels being replaced with these exact batteries.
Which allow an electric vehicle to be super fast,
super quiet, but also super clean.
But one aspect that has not thought of
or talked about as commonly is what we
do with all these batteries after they've
reached their intended lifespan.
Because once these batteries degrade to about 75% of their capacity,
these batteries will need to be replaced as they won't
have enough power to move the vehicle properly.
And this is going to be a big problem
because there's going to be millions
of these cars with each car having thousands of these cells.
We're talking about billions of batteries
becoming useless for these electric
vehicles and possibly getting tossed straight into landfill.
So what comes next for all these batteries?
Well, the obvious thing to do is to recycle them.
But while all the materials that make up
the battery are potentially recyclable,
separating them out is labour-intensive
and a complex, expensive process.
So what else could we do with them while we're
trying to optimise this recycling procedure?
Well, actually, these batteries can be reused for other purposes,
for things like off-grid power sources,
backup power use and solar-powered applications.
This way, the batteries are given a second
life by extending the batteries'
usable lifespan so that every bit of energy can be squeezed out.
And just to paint the picture of how useful this would be,
it's projected that in the year 2030,
there'll be 85 million electric vehicles sold worldwide
with the batteries having 1,000-gigawatt
hours of energy left in them.
And to put that into perspective, only 25 gigawatts of rooftop
solar panels have been installed in the history of Australia.
Now, that is a lot of homes those batteries could
be powering by giving them a second life.
OK, cool.
So we can reuse these batteries from electric
vehicles and other applications
in their second life and divert batteries
from landfill and save more money.
Sounds like a great solution.
But then the next question is, from all these billions of batteries,
how do we know which ones we can use?
This question turns out to be really important
because the shiny new batteries that
you put into the vehicle are not going to
be the same as when you take them out.
That's because they've changed from all the brutal discharging
and recharging cycles which eventually degrade the battery.
But we've also seen the worst-case scenario of
these degrading batteries in Samsung phones,
where they've been known to spontaneously catch on fire and explode.
This disaster costing $5.3 billion to recall all those batteries.
So we need to ensure we avoid these dangerous
situations at all costs by making
sure we understand the overall health of the battery inside and out.
But in order to understand how these disasters
are happening on the outside,
we have to delve into the battery to understand what's going on inside.
The solution we're developing at our lab at UNSW is to use X-rays,
which gives us a way of seeing inside the battery
and how it works without physically touching it.
And these X-rays are just like the X-ray scans you get in hospitals.
We have X-rays shoot at your body and have it detect on the other side.
That captures an image based on how different
materials absorb these X-rays.
So, for example, X-rays pass right through your skin and blood vessels,
but your denser bones absorb more of those X-rays.
So you see that difference in the X-ray scan.
For batteries, all the different materials used, such as the lithium,
the electrodes and even the metal casing outside
all absorb the X-rays differently.
And this reveals a two-dimensional image that gives
us a unique picture of what's inside the battery.
But at our lab, we go a dimension further
by using a technique known as tomography.
Now, the word tomography is made up of two parts.
'Tomo' comes from ancient Greek, which means a slice or a section.
And 'graphy' means to describe something by.
So much like the word geography is describing
something through the use of the earth,
tomography is describing a material through the use of slices.
And we do this by taking two-dimensional images
of the battery while it's rotating
in the X-rays to collect hundreds
and sometimes thousands of these images.
We then combine all these slices together to make
a complete three-dimensional model of the battery.
And with this 3D model, we can then explore
the landscape of the battery however we like,
zooming in, rotating, peeling back layers.
So that we're able to fully understand how every little hidden
component contributes to the battery's performance and health.
And with this 3D X-ray vision,
what we end up seeing are the layers of electrodes
inside the battery that are rolled up to
form the cylindrical shape that we see.
And one of the coolest things we can do with our 3D battery
model is to take it and unroll it virtually.
This way we can flatten out the whole wound-up electrode and get
a clear picture all in one glance without touching it at all.
This gives us the ability to quickly and easily explore,
pinpoint and discover any flaws or imperfections in the battery
that would jeopardise its performance or health.
And this would not be possible without X-ray tomography.
And what we've discovered are the growth of these foreign
objects inside the battery as it's being used.
These foreign objects are what we call 'dendrites',
which are one of the most insidious things that
can grow and destroy a battery from within.
These dendrites are microscopic whiskers that
slowly grow from tiny deposits of lithium.
They end up digging through the layers of the battery,
which could then connect parts of the battery that
shouldn't be connected to create short circuits.
And these short circuits allow a surge of electrical current
that can start fires and cause those exploding batteries.
And on top of all this cool analysis we can do,
we can use the same cool AI algorithms that we see in Tesla cars,
used to recognize stop signs and pedestrians to be customised
to recognise all these defects automatically.
And this really opens up the possibility of assessing
for the most useful batteries at an industrial scale.
To realistically pave the way for the wave of second
life batteries to be used in the future.
So as we transition into a world with clean, renewable energy,
we have to consider how we're going to extract all the potential
from all the technologies we're going to use to get there.
And while there will be hurdles and challenges to overcome, as humans,
we need to continually discover innovative ideas to solve them.
Plus X-rays and batteries have shown,
sometimes the best way to search for that spot is by looking inside.