Coating of powders for energy applications

Coating of composites for improved Li-S batteries 

Session Notes:


Mato Knez

CIC NanoGune




The application of Al2O3 to cathode materials of lithium-sulfur batteries may solve some of the critical issues of this family of batteries, which hinders their commercial use. In this work, the cathode of lithium-sulfur batteries is coated by ALD and an improved capacity of the system will be shown. We report on the optimal parameters for ALD application to sulfur-based electrodes and the physicochemical characterization of the cathodes. Large numbers of ALD cycles, especially at elevated process temperatures, result in considerable sulfur loss, which significantly lowers the cell performance. However, few-cycle ALD processes at optimized process temperatures aid a better cell performance. In the best case, the capacity of the battery system was incresed by 13% for low current densities and by 50% for high current densities with respect to the standard Li-S cathode.

0:00:01   Hello, everyone I would like to think he organizes for having me in this online meeting on showing
0:00:07   some part of Fallbrook. My name is Mato Knez. I'm working in San Sebastian in the north of Spain
0:00:12   and CSE Ngwenya Research Centre. And I'm going to talk about our approach to coat particles by a
0:00:17   lady for improving with himself for batteries. Why do we actually need to improve batteries? Well,
0:00:25   there's several reasons for that. Currently, we're using fossil fuels as main source of energy, and
0:00:31   we are converting this energy by combustion. And just of course, several issues were dead, and one
0:00:36   of them is the limited availability that in those sources are not renewable. At the same time, the
0:00:42   combustion of fossil fuels generates greenhouse gases, which are sooner or later going to destroy
0:00:48   our environment, which means we have to look for alternatives or in it is energy source. The
0:00:54   alternative is the use of renewable energy sources. However, those are really available at the point
0:00:59   of use. That means that remote, and we need to find ways how to more efficiently transport or store
0:01:06   and electrical energy, which is generated at those sources now, batteries are one of the possible
0:01:12   ways how to store energy and transport. And besides, most of us in our civilization, our days have
0:01:19   mobile phones, laptops and even cars which are running electrically, which means that we need tohave
0:01:25   better batteries, larger amounts off smaller and highly capacitive batteries.
0:01:32   The currently best type batteries on the market are the lithium ion batteries, which I used in most
0:01:37   of the mobile phones or laptops. It's similar, and they have some advantages. For example, of high
0:01:42   energy density. They have excellent sacking stability in the high Siri capability. However, they
0:01:49   have also limited specific capacity, and they contained in many cases on most of the cases some raw
0:01:54   materials and a couple composition. Therefore, of course, there are always alternatives. Better
0:01:59   alternatives searched for and one of the most promising types of batteries toe succeed the lithium
0:02:06   ion batteries on a so called lithium sulphur batteries.
0:02:12   What is special about sue, for in this context, the material is abundance and it's rather
0:02:17   environmentally friendly depends always in the context, of course, but the most important point is
0:02:22   this one here. It hasn't outstanding energy density with 2600 watt hours per kilogram. This is what
0:02:30   a typical lithium. So for battery cell looks like it's a schematic when you're outside, does up with
0:02:36   your metal electrodes. On the Catholic side, there is, ah, particle assembly off so four and carbon
0:02:43   and the carbon is actually needed. Another plane deals connectivity to the whole system because so
0:02:49   far by itself is non conductive. It's an in selector,
0:02:54   and this is what we already come toe the issues which lithium So for bettering approaches now that
0:02:59   minorities have, we have several problems on the one hand on the outside, the reactive metallic
0:03:07   lithium. I can interact with the electrolyte and also can grow dens rights by the solution and every
0:03:13   deposition, which at some point will grow towards the Catholic and make a short and in this way
0:03:20   destroy the whole cell. On the other side of the couple side. We have the problem off the sofa being
0:03:26   insulating, as I mentioned before, but we also have the volume change due toa dissolution off the
0:03:32   some four, and we have traveling effect off the Sioux for through the whole system, which is called
0:03:38   the shuttle effect, and this is one of the most critical effects, which hinders the implementation
0:03:43   of lithium sulphur batteries into the market. Nowadays, the shuttle effect means in principle that
0:03:50   so, for which is insoluble, is converted with lithium, it reacts toe soluble, highly soluble with
0:03:57   your political pints. Those can travel through the electrolyte through the separated from the cattle
0:04:02   to the untold, and they'll be reduced again and travel back to the Catholic, but also form those
0:04:08   insoluble lithium selfies, which then at the end of leads to war, leakage off so four on the
0:04:15   Catholic side in the corrosion off with your money and outside
0:04:21   possible way. How to prevent this issue is the cutting off the cattle side with a lady in this way,
0:04:29   trapping the so four and prevent the leakage
0:04:35   for the batteries. The capitals are typically produced by depositing a slurry off composite
0:04:41   particles with binders and solvents on top, off aluminum foil and then drying. So, given this
0:04:48   application procedure, the possible ways to apply a RD to cattles. On the one hand, the Catholics
0:04:56   could be prefabricated end on the A R D material deposited on top off the pre assembled cattle, but
0:05:05   also on the other hand, the particles off which the slurry consists could be initially courted by L.
0:05:11   D. In some guy's bed reactor, for example, and then the whole composite material for the process
0:05:19   towards a slurry. And then I'm blade coated on top off the electrodes.
0:05:26   We wanted to compare those two factionalization methodologies before we started in the first case
0:05:31   with a pre assembled Catholic. It means we, um when you picture a Catholic consisting off. So for
0:05:39   carbon Compass site, with our content off 1.8 milligram per square centimeter off so far and then
0:05:48   you some binder and beauty after in orderto deposit the slurry on top off the electoral and then
0:05:56   subsequently did a recording off here may and bottom
0:06:02   these prefabricated Catholics being solid sheets number, then very easily coated by a lady and
0:06:09   conventional lt chambers. That means Beckham chambers and be useful processes. Process temperatures
0:06:17   off 60 75 80 85 degrees C. And for each one of those we applied low cycle numbers. That means to 5
0:06:26   10 and 20 the maximum
0:06:30   so for his arm im acted material in dilithium. So for battery, which means that it's important toe
0:06:36   have s highest possible amount of some foreign, the Catholic. And of course, this means for the
0:06:42   preparation procedure for the publication that we lose as little as possible so far now, given that
0:06:49   we have the possibility toe off the super to interact with the precursor in general. But also we
0:06:54   have different temperatures in different numbers of cycles. We had to first of all, figure out
0:07:01   whether and how much so far we actually lose your in the Ailey process. And we indeed see a tendency
0:07:07   here that the temperatures play a role. The higher the temperature, the more so for we lose, but
0:07:13   also the larger. The number of cycles is the Muslim for views and given those effects. So these were
0:07:20   done by PGM Moses we have about how much will be lost. We decided that people for the I know I've
0:07:28   only the samples up to 10 daily cycles because 20 Ailey cycles let toe significant losses so far
0:07:35   already here. That means those samples are not relevant for a listen super battery anymore. The ECM
0:07:43   analysis showed basically similar images for all the samples which have that means the standard
0:07:48   electoral, which is doctor bladed so far covering compass, ICT and then 25 and 10 daily cycles at
0:07:54   various temperatures. So we have basically in this Ailey processing no degradation off the material
0:08:02   itself. The Catholic remains please morphological e the same as it was before the e d. Expecting off
0:08:10   aluminum. In this case, aluminum is green, um, shows on the expected image. It means with the
0:08:17   increasing number of cycles we have intensity, angry, increase off the green coloration. The sample,
0:08:24   which is in line with the expectation that means the number of cycles defines the amount off
0:08:29   aluminum or aluminum which we deposited. The electrochemical analysis, however, place a more
0:08:35   important role. Ghenda morphological analysis because we're dealing with batteries and we want to
0:08:40   improve them. So from all of our capitals which we fabricated meaning to five and 10 daily cycles at
0:08:48   each for different temperatures and also distended coupled, we've fabricated coin cells and then
0:08:57   analyzed that discharge rates by means off so called see rates and the result off all these and
0:09:04   others. This even though that to A and E and five daily cycles look pretty much similar. Among the
0:09:09   samples, we have the best improvement. I'm against the standard electrode in the case, off to a lady
0:09:16   cycles at 85 degrees C. What is this? This black dotted line here. So this was our champion among
0:09:24   all of the other intellectuals. The same applies also for the second ability. So we took a look at
0:09:31   the specific capacity in the case, off to a lady cycles and five daily cycles. They look pretty much
0:09:37   similar, however, with two Ailey cycles when we have a slightly higher specific capacity, which
0:09:42   keeps constant over more than 50 cycles and a little bit less in the case of five yearly cycles.
0:09:48   Which means that even though they are similar, um, again our champion here is the oily cycles
0:09:54   fabricated 85 degrees C. So this is the black dotted line here.
0:09:59   So our approach toe coat cathodes prefabricated couples by a lady resulted in an improvement. Means
0:10:07   eliminated position with only a few cycles on the cathode can improve the battery performance
0:10:13   specific capacity, and the reason can be to force, on one hand the cohesion of particles. That means
0:10:20   we have our particles, which are interlinked and bound or glued by Elmina by L. D. Which on the one
0:10:27   hand, can, um, maintain the physical contact between the particles and therefore increase the
0:10:33   electric conductivity, but also generate or keep poor's ferocity with a functional S service off the
0:10:42   carbons, which then will benefit the electorate absorption in the capital material. On the other
0:10:48   hand, we can, by means of a only bind the police all fights which will then reduce the transport in
0:10:55   this way suppressed the shuttle effect. Onda also minimize the dissolution off the so far into the
0:11:04   electrolyte. The details of this world can be found in this publication which we published just
0:11:11   earlier this year.
0:11:14   The previously described work waas probably not too astonishing as we were expecting an improvement
0:11:20   off the battery performance if you use a l. D, especially if you use few cycles because similar work
0:11:27   has been done already before. But for us, it was more off a learning process in order to understand
0:11:33   what benefit ale can do to batteries and how to handle it Now, in the next couple of slights I will
0:11:40   describe are initially planned approach, which means we're are thinking off the particles off the
0:11:48   powders composite powerless for the batteries. We wanted to do a lady coating on top of those
0:11:54   particles before assembling the electrodes, which means for that purpose, we had to construct a
0:11:59   fluid eyes bad reactor. And then we did this some in collaboration or with help from our colleagues
0:12:05   from the DEA, Delft in the Netherlands from road phenomena. And here we used the conventional
0:12:14   composite powders in a food as bad reacted didn t m able to process all women on deposition and then
0:12:21   made the slurry out off those palace which were pre coated by L D um, and fabricated the thoughts
0:12:30   with them. Now, the good thing about this is one specific point. If you look here, we have two
0:12:37   different concentrations off so far which we can apply in the food as bed reactor. What 0.8
0:12:46   milligram per square centimetre is one of the standard mixtures off carbon with so far. So this is
0:12:51   the amount of some form. And if you increase this, um, sue for load in most of the cases, if you
0:13:00   create a slurry and then make the Catholic, it will end up in cracks. So 1.88 is the safe side, or
0:13:10   for making the capitals on the other hand, if you use those composite powders you can already hear
0:13:17   increase, um, the so four load and an increased so follow social lead toe a higher capacity and then
0:13:25   try to make the slurry Andi fabricate the coupled. And this waas one of our approaches which wanted
0:13:31   to investigate. We wanted to see whether we can use the fluid as bed reactor at the Ailey process in
0:13:37   order to increase the so four load for the powder. And in this case on this way, increase the
0:13:44   capacity off key battery.
0:13:49   The process was performed in the home built from guys bed reactor. We run it at 90 degrees C and we
0:13:55   applied similar to before 25 10 and 20 cycle numbers early second numbers. In order to call the
0:14:01   particles, of course, we do not expect to have a complete coating the particles by alien. This is
0:14:07   also not desired because aluminum is an insulator and we want oh, have a conductive material here.
0:14:13   But the binding itself this is one of the key, So the substrate for super couple composite particles
0:14:19   as conventionally used in lithium sulfur battery research and because it's of course TME and water
0:14:26   as a standard because or a Lee from icy PMS. We could see that from the change off the content off
0:14:36   aluminum is in line with the expectations. That means with the increasing number of cycles, we
0:14:41   haven't increased among off aluminum in our complicit.
0:14:48   We did some TM imaging and ADX mapping off some particles which we called it. And what we can see
0:14:55   here is the green parts. We have aluminum and oxygen, so this is significant for a woman of oxide.
0:15:03   We haven't increased signal off aluminum and oxygen, which indicates higher load with the number of
0:15:14   cycles. So the aluminum oxide is there even though it's not interconnected. That means we've rather
0:15:21   large aggregate or particles instead of a complete coating. And this is, of course, what we actually
0:15:25   want tohave. On the other hand, we have also sue for and carbon nothing that means are particles or
0:15:31   composite particles are still there. We have a significant amount off before you present, so it did
0:15:38   not finish in. This is off. Great importance for our aim, namely toe have, um, s highest possible.
0:15:46   So for loading our composite material for a better performance
0:15:53   refund by a dynamic light scattering that the particles which we process in offload as bad reactor
0:15:59   on aggregate. It means the more ale de cycles we apply, the larger is the average particle sized.
0:16:07   That means theologian, um, oxide excess glue and got in this case, and the particles are at the end
0:16:14   with 20 cycles well above the size which they showed originally.
0:16:21   But the sofa loss is one of the most important parameters in our compass site. We want to lose as
0:16:27   little as possible, so four and therefore analyzed all the samples which you produced by T. J. A.
0:16:33   And we figured out that low cycle members do not really result in a significant loss. But if you go
0:16:39   towards 10 and 20 ale the cycles, um, this obviously results in our evaporation or binding or
0:16:48   decomposition of the soup or and therefore to a loss in our compass ICT. I'm for us, the upper limit
0:16:58   off. So for loss, which we found acceptable waas 15% it means we omitted also in this case, like in
0:17:04   the previous case, the 20 ale de cycle processed powders because the super loss was simply too high.
0:17:12   The rest was electrochemical analyzed de ECM analysis saw the morphological characterization off, or
0:17:21   cathodes which have been used from our partners. They gave us a very, very interesting insight. So
0:17:26   know what you see here is the standard Catholic produced, with 1.8 milligram per square centimeters.
0:17:32   Hoover, which results typically incorrect information on which then eventually decreases the
0:17:41   capacity off the veteran. So this is awesome, something which is very well known, and this 1.8
0:17:49   milligrams is the upper limit that you can apply. It could go higher with a super amount. Such a
0:17:54   picture occurs. That means the interaction between the particles is weakened and also the
0:18:00   interaction between the slurry and substrate did the electoral itself the home which results in the
0:18:08   elimination and respectively, a little softy off the coupled. If you do apply a little powders, try
0:18:15   it toe slurry, a fabrication and the cathode application. We obviously increased the interaction
0:18:24   between the particles and also the direction between the particles from the slurry and the Catholic
0:18:32   about the current collector. And you see this in this case that after two and five daily cycles for
0:18:39   both cases on 50.8 milligrams, so four per square centimeter and 3.6 we don't see any cracks. That
0:18:47   means we have a homogeneous, um, situation where we don't have a least not obviously expressed a
0:18:56   cranks, which could then potentially lower the capacity or make the battery fail. If you increase
0:19:04   the cycle numbers to 10 we have, ah, currents off some cracks in the in the films here, which we
0:19:12   don't exactly yet know where they come from. So it is a little bit off a speculation, but most
0:19:18   likely here, the aluminum amount or aluminum oxide amount is too high. End changes completely the
0:19:26   waiting properties off the whole material.
0:19:31   If you take a look to the electrochemical analysis and consider the specific capacity which we
0:19:36   measure them from our batteries, which we assembled soul again, used coin cells. We see an increase
0:19:42   in the specific capacity for all ale, the processed samples compared to the standard sample, which
0:19:48   is great here, and it depends a little bit on the point of view. So two or five LD cycles are, um,
0:19:58   both very, very much improving the specific capacity. But together with the consideration off the
0:20:07   cycle ability, where on the five yearly cycle sample all performed off the others. We have toe
0:20:14   choose our champion and our champion in this case was the five Alieu cycle samples example which
0:20:22   significantly improved the standard cattle. But for the case off 1.8 milligram per square centimeter
0:20:31   if he doubled soup followed in the composite powder before a leader position. We have a very
0:20:36   interesting situation, so the discharge rates they're increasing for lo discharge currents, but
0:20:44   decreasing or high this judge currents. There's a very, very interesting development, however, on
0:20:50   the comparison here, with a standard system, is not really optimal because the standard electrodes
0:20:57   are produced with 1.8 milligram per square centimeter, which means that a direct comparison is not
0:21:03   possible at all. And the standard Catholics cannot be produced with diesel models.
0:21:12   If you then add to the comparison 1.8 milligram parts off for a centimeter. We have, ah, very nice
0:21:20   picture here, which shows us that the higher soulful load benefits the low see rates. Now that means
0:21:27   we increase the specific capacity of the system at lossy rates. While it is opposite in the highest
0:21:34   rated. That means once again to Muslim. Here is clearly better in a case off the 1.8 Millikan. So
0:21:42   for possible centimeter, if you take a look to the results, they tell us that annulment of the
0:21:49   position so a leader position point. Our Super column comp aside before assembling the cathode is
0:21:56   clearly beneficial. But the aluminum the position will result in a better cohesion off the particles
0:22:01   in this metal on the one hand, eliminate cracks and holes as we could see from our CM images. That
0:22:07   means delamination and cracking will not occurred it easily, and therefore the electronic
0:22:13   conductivity and the electrolyte impregnation into the powders into the coated cattle will be
0:22:20   improved. But also what we saw is that the sofa loaded can be increased. I understand. Did Cath
0:22:28   thought the sofa loading is limited toe? A maximum of 1.8 milligram per square centimeter, we can
0:22:35   hear go up to 3.6. That means we can double on the loading of super, which is the active material in
0:22:41   our case. And this clearly can increase the capacity of the system. I gotta hand Also, the
0:22:47   deposition can bind, the police will fight. It means the alumina canon trip. So for in some way. And
0:22:53   these were blocking the air transport. It means the shuttle effect will be diminished because young
0:22:59   women are protects and shields so far and also on the super Bill. I'm not that easily dissolve in
0:23:07   the electrolyte. It means, um, Alumina has a clearly beneficial effect here
0:23:14   as a conclusion from this part of the book is we have found on interesting alternative for the
0:23:20   fabrication off the lithium sulfur cathodes. It means if you use, um food as bed reactor, any kind
0:23:29   off part of male DeCota with only a few cycles in our case, it was finally cycles off. Alumina off
0:23:37   the sofa. Kabul copas. Before assembly of the Catholic, you will be able tow, assemble electrodes
0:23:46   which are crack free and hold free. And you can even increase the soup for loading. And this is one
0:23:53   of the most important points because so far is the active material in the hole with simple battery,
0:23:59   that means increasing the amount of before they'll also increase the deeper the performance off the
0:24:04   battery. Of course, that means at the end we haven't improved capacity, which we have shown in our
0:24:10   coin cells, which were which was fabricated. And this specifically means that great day 1.8. So the
0:24:17   standard amount off sue four in the compas ICT. We could increase the specific capacity compared to
0:24:23   the standard system by 30% at low see rates and at high sea rates, we could even improve it by 50%.
0:24:30   And for the lossy rates on increase off the soup before also increase the specific capacity it means
0:24:37   here. Compared to the standard system, we even reached 60% off improved. But this work most so
0:24:44   interesting that we applied for a patent for it.
0:24:49   Finally, I want to thank the members of my team for doing a great work on for the specific work here
0:24:56   on the palace. I want to thank Sarah Gothia. She did her PhD on his work and she did an excellent
0:25:02   job. And also Michaela, our technician who built up the food as better reactor bond, made the whole
0:25:10   thing run. But also all the others in the group who contributed in some way to the work. Then we
0:25:18   have our partners etc. The tech, who are specialists in better research. And this project was done
0:25:24   in cooperation with them. So are all the battery testing and assembly was done. Synthetic. Andi,
0:25:30   these are the people who predicted the world can see the tech. I also want to think route from woman
0:25:37   and I'm yellow from you left for helping us with the assembly off the food as bed reactor. And of
0:25:41   course, all the funding which we received from the curve as Spanish government, the bus governments
0:25:47   and I want to thank you for your patients.