I've got to be honest, one thing I never imagined
I'd be talking to you good folks about is the idea of making batteries from trees. That's
about as counter-intuitive as it gets right? I mean wood is an electrical insulator not a
conductor isn't it? But then again I've been constantly astonished by the stuff I've learned
from the scientific community over the years I've been running this channel, so I suppose
nothing should really surprise me anymore. And sure enough there really is a battery coming
to market very soon that uses wood as one of its raw materials. I made a little mock-up of what
I thought a wood-based battery might look like, but I wasn't 100% convinced I'd got all the
details strictly accurate and I haven't managed to get any power out of it just yet. So I contacted
one of the lead scientists on this new wood-based battery project to see if he could offer a
bit of help, and it turns out that just like so many of the other technologies I've covered,
there's much more to this one than meets the eye! Hello and welcome to Just Have a Think. Well the
first thing I discovered was that I was completely off course with my little design concept here,
which is news that I'm sure will come as no great surprise to any of you. So after hours of
careful toil to craft this particular work of art, I'm afraid it has to go straight into my
waste basket of ill-conceived ignorance. The real thing is of course far more sophisticated
than my pathetic effort and it's the result of many years of research and development by a team
of scientists at Lingkoping University in Sweden led by professors Magnus Berggren and Xavier
Crispin. And it was Professor Crispin who did his best to gently steer my somewhat confused
mind through the various processes involved in producing the battery when I caught up with
him via Zoom recently. So here's my best attempt at interpreting how this particular energy
storage system works. Let's start with the tree thing first of all. The material that's
actually of interest to the team is lignin, which is the gluey substance that makes up about
25% percent of a tree's structure. The rest of the tree is made up of cellulose and hemicellulose. So
just to be completely clear, there aren't teams of lumberjacks going out into the Swedish wilderness
and hacking down entire forests to make these batteries. They're actually recovering the lignin
from the paper milling industry, which only uses the cellulose part of the tree and which usually
just burns lignin as part of a waste slurry known as black liquor. Now here's where it all gets a
bit technical. Professor Crispin explained that lignin is an aromatic heteropolymer, which means
its structure contains small rings of benzene. Those benzene rings contain specific types of
electrons called Pi electrons which, under the right electrochemical conditions, can be liberated
without destroying the benzene ring itself. Those electrons could in theory be directed
through an electrical circuit to do some work before returning back into the benzene ring at the
end of the process. Moving electrons is basically what a battery does so it looks like we've got
something potentially interesting going on here. But as I mentioned at the start of the video,
lignin is not an electrical conductor it's an electrical insulator, so those Pi electrons don't
naturally want to go anywhere at all. The insight, discovered in 2012 by another Linkoping Professor
called Olle Inganas, was to find a way of bringing electrons to and from the benzene ring by creating
a nanocomposite material of conducting polymers which, as the name suggests, is a specific
class of polymers that can conduct electricity. Down at that mind-blowingly minuscule nanoscale
the polymer chains act like molecular wires which can then be embedded into the lignin to facilitate
the movement of electrons into the benzene rings to store a charge. Professor Inganas' achievement
was quite the breakthrough and it kick-started a decade of research and development
bringing us right up to the present day in their relentless drive to get the cost of the
battery down to something that could compete with Lithium-ion batteries the researchers came to
realize that the original polymer material was probably going to be way too expensive. So the
hunt was on for a cheaper alternative. And it turns out the solution lay in plain old carbon
which is an extremely abundant material that can do the same conducting job as the expensive
polymer. But it still needed to work at the same nano scale to provide the molecular highways
for those electrons to flow along, and that meant utilizing another technology we looked at
in a recent video - dry ball milling. That step crushes the carbon together with the lignin which,
for reasons of science that even the scientists aren't 100% sure about, causes the carbon to
mix with the lignin to become a nano composite material enabling the electrons to travel along
the carbon molecular pathways to reach the aromatic electroactive component of the lignin.
On the other side of the cell is a zinc electrode and the whole thing is contained in an electrolyte
made of a super concentrated solution of potassium polyacrylate which is an absorbent material
commonly used in babies nappies or diapers. There are some really tangible advantages in
creating a battery in this way, not least of which is the avoidance of problematic components
like lithium, cobalt or nickel in the battery chemistry. The volume of paper being produced
today is so vast that according to Professor Crispin's research team even if you made all
the batteries in the world with waste lignin from paper mills you'd still only be using a small
fraction of the immense volume the paper industry produces. All the other materials are abundant and
inexpensive too and the potassium polyacrylate in the electrolyte also has the added advantage of
eliminating the fire risk that occasionally besets Lithium-ion batteries. The technology is now being
commercialized by a spin-off company called Ligna Energy, founded by the three professors Inganas,
Crispin and Berggren. The target for the first generation of lignin-based batteries is to provide
power for internet of things or IOT devices. As Professor Crispin pointed out, once 5G and 6G
become the ubiquitous over-the-air communication standards then the internet of things will
turn into the internet of everything. And that means there'll be billions and billions of tiny
batteries all over the planet, each performing its own very specific function for a very short
prescribed length of time. For example a light or heat sensor sending a brief signal to the internet
to control the on off function of a particular device. All those sensors and signallers need
power which will need to be provided by a battery. The goal is to use lignin-based
batteries in a concept known as Zero Energy devices first proposed by the
Swedish telecommunications giant Ericsson. Now that might sound a bit like the proverbial
perpetual motion machine to you and me, but it really just means equipping these tiny machines
with their own small solar cell that can recharge the unit's battery. That means the battery can
be much smaller because it doesn't have to carry the energy capacity to last the lifetime of the
device. And it means you never need to replace the battery either because it gets a continuous
supply of energy directly from light. Ligna Energy is working with another Linkoping University
start-up company called Epishine who are using roll to roll printed technology to produce long
films of flexible plastic solar cells using conducting and semiconducting polymers that can be
processed from a solvent. It's an incredibly cheap and efficient way to produce the huge volumes
of light energy harvesting devices that will be needed in the coming decades as we move towards
a world where every appliance and almost every surface we interact with will have some kind
of sensing and measuring technology constantly pinging data back to a centralized internet-based
controller designed to optimize Energy Efficiency. To someone of my vintage it's really the stuff of
pure science fiction, but nevertheless here it is in real life about to arrive in all our lives in
a very big way. But Ligna Energy doesn't want to stop at tiny devices. They see no reason why
lignin-based energy technologies can't be used at the other end of the scale for energy storage
on national electricity grids to complement or even compete with existing lithium-ion battery
banks. There is still some development work to do before they reach that lofty goal though.
The potential difference across each cell is currently about 1.3 volts and the energy density
is currently about 40 watt hours per kilogram which is similar to lead acid batteries but
without the toxic lead content of course. It's not yet at the level of lithium ion though,
which typically has an energy density of more than 200 watt hours per kilogram. It's a parameter that
Professor Crispin is confident can be increased in future iterations of the lignin battery by
applying an extra step of clever chemistry to the lignin itself to enable it to store more charge.
They already have a pretty robust and stable setup though. Lab test batteries have achieved several
thousand cycles with very little loss of capacity. So the future could be bright for this particular
energy storage solution. And the world may not have to wait too long to see a lignin-based
cell in real life. Ligna and Epishine are working towards production of these small thin
film version within the next two to three years. So what's your view on this one? Do you feel
this could be a more sustainable alternative to the current crop of lithium battery
technologies on the market? Are you looking forward to an internet of everything or do you
see it as some sort of dystopian nightmare? Whatever your view, the place to leave
your thoughts as always is the comments section below this video. And I'll be
very interested to see what you think. That's it for this week though. Thanks as always
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