It's a material scientist's dream.
Imagine there was a battery material that just wouldn't degrade at all.
The material would somehow stay in the exact same state of health for hundreds or maybe
even thousands of years.
And every time the material would develop first cracks due to mechanical, thermal, or
acoustical shocks, the material failure would just magically heal itself.
Maybe like a forest or like a plant or human skin.
Is that even possible?
We ask ourselves, chemically speaking?
Battery generation brought to you by Celeste.
Welcome to Battery Generation, Professor Dr. Mitana Berritibar.
Thank you very much for having me in this podcast.
Let me introduce you to our audience really quickly.
You are a professor for electrical engineering and power electronics at Freya University
of Brussels in Belgium.
You are the head of Battery Innovation Center in the MOBY research group at your university.
MOBY is an innovative research hub for electromobility.
And your expertise, among others, includes emerging battery technologies, battery manufacturing,
self-healing properties, and sensor integration.
So let's talk about self-healing batteries.
Would you first of all describe that term to our audience, please?
What is a self-healing battery?
What does that mean?
Yes, well, self-healing batteries is something that is very novel.
In the battery scientific world, we are now researching it.
And it's becoming more and more important topic.
And actually self-healing what we try to understand and as the name it says is try to
protect the batteries from degradation mechanisms that are occurring in the battery cell and
at the end expand the lifetime by autocorative processes that we can have in the battery
cell.
Let's dive in just a little bit here.
So on the one hand, you mentioned prolonging the lifetime of the battery itself.
And the second part would be some corrective mechanism.
So are we actually talking about a degradation that took place and that you are able to revert
with your self-healing battery, much like maybe if I cut my finger and itself heals?
Is that comparable?
It is comparable, yes.
So at the end in self-healing batteries, what we have is that, for example, we have different
materials, different compounds.
One example that I like a lot is the usage of silicon.
Now we are using silicon more and more in our batteries because of the properties that
it gives.
But silicon has an issue because when we are charging and discharging the batteries through
the cycling process, the silicon expands.
So that means that of course it can at the end break in different compounds and we will
have a capacity decrease on the battery.
So we can use it for shorter cycles.
So if we use a self-healing property, we can use, for example, a save of healing coatings
in which we will protect that silicon and we will try to stop that breaking from the
expansion of the silicon.
And in this kind of concept, silicon self-healing properties relies on.
Just to get that clear, once the silicon is broken, could the battery repair that silicon
or is it all about preventing it from breaking?
There are different concepts and of course some of them try to activate an action on
the silicon that is broken.
Other kind of actions will try to protect and keep the material inside.
So it's both.
It's both basically.
My first question actually is silicon is already used in lithium ion batteries.
On the end outside, it's usually doping the graphite there.
Is there self-healing batteries on the market already?
I would say not yet, but at least from my perspective.
However, we are now on it.
And this means that the statu-sen, which we are now at market level, is that we are
developing the different materials, let's say, with the self-healing properties.
And these ones are now tested on a prototype, tested on a battery cell that we can develop.
And then from that at the end, we will need to test.
And what happens with some healing properties?
That this comes with degradation and comes with time.
So then we need to at the end test the battery for a period of time.
And in that moment, we will be able to have the self-healing batteries in the market,
in at European level.
If we take this concept to the end and say we achieve all that, do you have an estimate
of how much additional lifetime you could actually achieve for a battery?
Are we talking about a forever battery that just never dies, that I could just maybe
send to space to some remote space station with equipped with some solar and then they
just have electricity forever?
That's for sure the aim to have this battery that will last forever.
However, what we are doing is developing our research, understanding by different parts.
Of course, at a certain point, everything comes together, self-healing, sensors, thermal
management and so on.
So at the end, we are going to have definitely, if we compare to the starting point of batteries
in 1990 by Sony, we compare with that technology, the way that we have done already, it's huge.
And I really would like to say that the way that we need to go ahead is also huge.
So we will definitely have longer lifetime batteries in the future.
Can't you just name a number, just an estimation?
How much are we talking about?
Is that, I mean, all these efforts, are they leading to, let's say, double lifetime
or are we talking maybe 5% to 3% more lifetime?
I don't think we will stay on the 2% to 3%.
I would aim more for double the lifetime, however, that's a little bit too much to say.
But yeah, it would be, I think it will be quite big the step that we are taking.
But we should not understand self-healing as always coming back to ideal or scenario
or a fresh battery with the beginning of life point.
Of course, self-healing will try to recuperate or try to enhance the situation of the battery,
but it's quite difficult that we will always stay in a fresh, limit battery state.
So we will definitely go lower and lower with the different degradation mechanisms
that kind of occurring.
We will go to lower capacities and higher resistances.
Could you just summarize once more the reasons that, so to say, drive the research on self-healing
batteries, what are the advantages you want to reach at some point?
This is a very interesting question indeed in the battery world.
We are now in a situation, in a transition in which because of this energy transition
that we are facing, we need to have more batteries.
This is an energy storage system that has very good characteristics and we need to use
them more and more.
But of course, there is an issue with raw materials.
So then we need to use the batteries that we have today or that we are going to manufacture
in the coming years for longer time so that we are more sustainable.
Are we actually talking about just changing, for example, lithium-ion batteries a little
bit and then making them into a self-healing battery?
Is this an entirely new set of chemistries or a completely new battery design that we
are talking about?
So is it something we can just put on the existing technology or is it something that
needs to be redone entirely?
Yes, one may think that this is a very novel topic.
So you may think that maybe this is happening only in novel technologies.
But when we think about how the self-healing properties or understanding comes from, this
comes from degradation.
This comes from the aging that is occurring in lithium-ion batteries.
In this sense, many of the aging or degradation processes that can happen on a cell that is
already mature, that is already manufactured, that we can buy, can be exactly the same degradation
that can happen, for example, in new coming technologies like solid-state batteries.
So the self-healing concept that we are developing can fit in many different technologies.
We can talk about generation 3, generation 4, generation 5 even.
And then we can, from those self-healing properties, understand which one would fit which technology.
As I understand it, there's lots of researchers focusing on self-healing batteries such as
mathematicians, people that do modeling engineers, chemists.
Is there actually biologists working on batteries such as organic materials?
You could maybe imagine when now comparing self-healing to maybe human skin or a forest
or something, is there people from biology working in your research groups?
Actually, I would think that it's a little bit of a mixture of everything.
Of course, the understanding or the first idea of self-healing comes a little bit from the
human understanding, from nature understanding, as you are saying a little bit more biological
understanding.
So that's a little bit the starting point.
Why not applying this concept in batteries?
But of course, afterwards, needs to be a chemical process, needs to happen in the battery,
with the materials that we are using.
Then, at the end of course, when you understand how can you apply that, you need to optimize
that process and you want to apply that process.
And then of course, what we need to have is an engineering process.
So I would say that at the end, it's a mix of the different kind of walls that we have.
Let me come to that engineering process just a little more, because recently there have
been a lot of headlines about sensors in batteries, maybe even in cells.
So we were wondering, if I'm going to have a self-healing battery, I need to somehow
know it stayed, right?
I need to know whether it already degraded.
So I would imagine there would be some sort of sensors required.
Is that part of the concept for self-healing batteries?
Can you maybe elaborate on that?
Yes, this is something that is happening now and it will start very soon on how to combine
both worlds.
We are understanding in one hand which kind of sensors can we use to understand the battery
properties?
And on the other hand, we are as well understanding which kind of self-healing properties can we
really track or can we really interact on to have a better lifetime batteries?
And what we need to have of course here, very important, is a trigger.
It's a triggering that will at the end say, okay, the self-healing functionality needs
to happen and why?
Activate.
Activate, yes.
And then of course, when does this triggering need to happen?
When do we need to say activate now?
Can we understand from the different sensors which is the status of the battery?
So this is something that is now coming together.
You probably need to define some sort of threshold where you say if maybe the voltage
goes underneath a certain level of the cell or maybe temperature, do you already maybe
know which sort of sensors you need?
Do you need to know the voltage, you know the resistance or do you need the temperature
maybe?
There is many of the different sensors that we can use and what is happening now is the
understanding of which sensors could be successful for the battery world.
This is what we are now understanding.
And there are many different kinds of sensors.
There are acoustic sensors, electrical sensors, mechanical sensors, temperature sensors, electrochemical
sensors.
So for example, if we can try to understand temperature sensors, this is something extremely
important.
Temperature is a threat sometimes for the battery.
We need to control it very well.
So if we understand precisely at the cell level, where is the concentration of maximum
temperature and how much is that temperature?
We are understanding a lot of the characteristic of the battery.
We can understand as well electrochemical sensors like impedance spectroscopy.
impedance spectroscopy can give us in an overall resistance understanding of the battery, but
also much more detailed understanding.
But that already gives us a lot of information of the battery performance as well.
And if we are talking about for example mechanical sensors, we can have stress sensors.
We can link this to the previous topic that we were discussing on silicon.
If we understand that stress factor of the battery itself, we can prevent gas formation
in the battery that will lead maybe to a hazard.
So that we need to link very well with sensor, a combined, which kind of self-healing property.
Would you once more tell us why sensors in batteries and self-healing properties are
always mentioned together?
Aren't they actually two very different separated research areas?
We can treat it as separate areas.
We can have batteries only with sensors.
We can have batteries only with self-healing properties.
But now the next step on the research actions on batteries is to understand how can both
be combined together so that this will be a little bit the engineering that we were
saying before.
The engineering effect of both togethers because of course we need to understand that self-healing
properties maybe they need to get activated when they need to get activated and not before
and not later.
And this will be something that for example the sensors can really provide this information.
And then in that sense, if we can try to combine both of the walls, however independently
they can definitely work as well.
That's a great future outlook there.
But let's take one step back, Professor Berreethibar.
If I buy an electric vehicle right now, is there any sensors already inside the battery
packs?
Sensors is something that now in the battery scientific world is under research on different
fields in different topics.
We can have sensors at manufacturing level, in the manufacturing line to produce better
batteries.
We can have sensors on the cells as we are saying inside the cell or on top of the cells.
And we can have even sensors at the battery pack.
Normally today if you would have an electric vehicle, you would have sensors for sure at
the battery pack.
These sensors they need to be there for understanding thermal management and thermal actions that
needs to be done at the battery pack level.
However the sensors that we are developing now would be more into the cell level, inside
the cell or on top of the cell.
And this of course there is a big difference in understanding the different properties
of each of the cells.
How can I picture that whole large?
Are these sensors that are already put into a battery pack?
And then the sensors that you might want to put into every single cell?
Is that maybe comparable with the top of my pencil here?
How large are they?
Yes, it can be comparable to that.
Of course depending on the sensor it is a space is critical.
A space is critical for a battery pack.
So the sensors need to be as small as possible.
So the sensors that are inside the cell even more because of course we need to go over
them with different layers of the materials that we are using to develop the battery.
But of course on top of the cell these are normally printed sensors that can be very
flat and they don't have nearly any space that they take.
Then you need to communicate that data between the cells.
So you don't use cables of course but still wouldn't that also just require a little bit
of space because you don't only have the poles to connect but also the data links.
Of course ideally this will come also there are some research sections happening here.
How can we connect and understand the signals of each of the sensors?
So for that at the end what we are aiming us is to have a cloud computing is to have
wireless connection where we can understand each of the data and what is happening there.
So maybe in the near future my battery will have a longer life if I have good wifi.
Well I hope that it will not rely on your wifi but it will be definitely connected.
It really helps on having better understanding and faster responses on the different algorithms
and management systems.
Let's say every single cell of a module is now equipped with a sensor and you get the
data, how much capacity, how much performance you get out of a cell.
Wouldn't you need in the next step and very individual cooling and heating setup that
I don't know might want to cool or heat up different cells.
For example when I accidentally supercharged my battery in a very cool environment there
might be some cells that degrade it much faster than the other ones and might want to be treated
very differently from the cooling and heating system.
Is that possible in the future?
It's possible definitely it can be even enhanced with the usage of different sensors per cell
but I can say that there are many activities already ongoing today for the better development
of the battery thermal management systems.
In this case we are having different kind of thermal management systems and cooling systems
that up to now it has been a little bit either air based or either liquid based with maybe
a refrigerant that we can use but we are more and more using hybridization of both and even
phase change materials that we can use for the cooling systems.
But on top of that there are other activities that are ongoing today that we can apply today
like for example smart charging as you are mentioning of course when it's very cold we
need to maybe have a heating process in the battery so that this charging process can
be faster and can be with less aggressive to the batteries and in the same way for example
when we are going to fast charge, fast charge produces creates higher temperature creates
warmth in the battery so how to do this in the best way depending on the battery characteristics
of it and what is happening a lot as well is because this is a lot of data this is a
lot of understanding algorithm development this at the end creates a lot of usage of
the computational effort of the microcontrollers so then at the end we need to have as well
other kind of solutions like hardware in the in the loop cloud based technology that we
can have more accurate and quicker understanding on how to charge our battery for example in
different temperatures.
Let's now talk about battery safety as well I know from a Chinese electric vehicle manufacturer
that actually monitors all of its batteries via the data you just mentioned and they
are actually able to see the state of health of all their batteries including if someone
has a problem with her or his battery so it's probably also a topic for battery safety
right I mean if you monitor all these data maybe a smart battery can lead to less accidents
right yes totally we are talking about the longer lifetime however of course sensors self
healing and thermal management this is indeed highly linked with safety so per definition
the we will have safer batteries however the batteries that we have now in place are of
course very well equipped and safe already but we will have even safer understanding
batteries.
If I actually have a really self healing battery just imagine the concept comes to pass and
is there I would probably not even need to worry about the battery malfunctioning so much
because if it does it either shuts down way before if it can't handle the self repair
or it will self repair and I don't get ever ever get to that point where I actually have
a critical malfunction.
So yes of course this is something that is now changing the state of health normally
relies a little bit on the capacity decrease of the battery but now when we are talking
about self healing when we are talking about sensor implementation we are of course understanding
the capacity decrease but we are also understanding the resistance we are understanding the specific
degradation mechanisms that are happening and we are understanding if there is full
variation if there is micro cracking if the solid electrolyte is increasing how much
so then in that sense the battery management system can go now to novel concepts in which
it will rely on other aspects as well and it can in that sense have a better and more
accurate understanding of the battery phenomena.
Let's now skip to the topic of manufacturing these self healing batteries smart batteries
I am pretty sure that it is very costly to implement all these sensors inside a battery
how would you convince a manufacturer of producing these self healing batteries and
a serious question now do you think a manufacturer even wants to sell them if they existed since
self healing batteries would probably be the last battery they ever sell right since it
self healing and I don't have any incentive to buy the next one.
Well of course it's tricky it's already tricky to manufacture the batteries that we have
in place to have them very very equal to each other with a very accurate process so including
sensors and including self healing functionalities and materials that creates a new challenge
on the manufacturing but we are very well prepared I would say at European level battery
manufacturers at Europe they are very well involved in European projects that are ongoing
with this self healing and sensor activities so they are already understanding how to do
this but of course we need to wait to understand which are the sensors that are going to be
applied and where to locate them and how many to locate them and the same with the self healing
but if I would put myself on if I would be a battery manufacturer I would say that why
not to have the best quality and longer lifetime batteries because at the end we are now facing
a technology that will be farther improved and we will go to novel technologies and we
will go to more sustainable technologies so we will need to go into this race so I don't
see a problem with having long lasting batteries if I would be a battery manufacturer of course
you mentioned before that you have so much data that maybe you will process over by a
cloud computing just a quick question do you see AI or machine learning as having a part
of of that self healing battery to to to kind of analyze it or is that something you can
actually already engineer with the equations we have with the knowledge we have this is
I would say well established when we are talking about the self healing sensors thermal management
as well we are using I would say today everything based on on machine learning we are developing
on a European project Spartacus state of X estimation algorithms for the the performance
and understanding of the sensors that are implemented in the cell and this definitely
it's applied already because we already have a huge background and a huge understanding
on how to do this already with not sensorized cells or non self healing batteries so this
is something that we directly can apply definitely we need to have a basic understanding and
proof of concept but from that moment on we apply directly smart tools to develop the
next coming technology with the machine learning and artificial intelligence tools.
Another topic I'd be really interested in would be a second life of batteries you talked
about collecting all these data from the cells the single cells but the modules and packs
as well isn't that something someone in the future could be interested in when buying
these used batteries.
Yes I think it really makes a difference if we understand that for example a battery
is already used in a passenger car and needs to move to a second life scenario if we understand
that the batteries have self healing functionalities has sensors to understand better what's the
current performance and the status of that battery I think it will be a big difference
and it definitely can enable and use it for longer lifetime and more cycles in a second
life scenario with a safer battery as well.
In my mind I was just comparing it to the kilometer counter in the car which is maybe
just a very crude number to estimate how worn down a car is but with all that sensor data
I would actually be able to when selling a battery for second life to label it very
precisely on what maybe lifetime to expect from it and what kind of usage it would be
suited for because I have all that.
The detailed battery passport is something that is now ongoing and in that same way we'll
as well be an enabler for second life because we will understand what is the history of
that battery what's the actual state of that battery but of course here what is really
key is the understanding of remaining useful life algorithms and the state of health algorithms.
This really provides the real understanding of if we can use that battery or where can
we use it as well in which kind of applications and on grid applications some applications
are they need more let's say higher requirements than others and that is key to understand
how to match them well and with the sensors and self healing will be even more feasible.
Last question for this podcast what do you think is the outlook and the goal of your research
when you look at the next let's say three to five to ten years will we see these self
healing batteries on the market and if yes what applications is the first one to target?
I totally believe that we will have this self healing and sensorized cells although we will
need to wait a little bit to see it on an application what we are trying to prove is
the proof of concept is the self healing concept is the sensor concept how to apply this in
the technology that we have now in place and it will come in the future and of course one
of the targets is transport it's passenger cars it's buses it's trains it's everything
that we need to to to yeah to electrify more and more on transport.
Thank you so much for this talk professor Berithi Bar thank you for your time and your
expertise dear listeners now it's your time please comment in the comment section or send
us an email that's hello at battery generation dot com.
See you next time thank you so much bye bye.
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