The dry electrode coating course of has the potential to allow the manufacturing of higher, greener, more cost effective batteries. It depends on superior fluoropolymer binders with Teflon™
For a number of years now, Charged has been reporting on how dry electrode coating processes have the potential to revolutionize battery manufacturing by eliminating the usage of hazardous, environmentally dangerous solvents. Taking the solvents out of the method can translate to massive financial savings in price and ground area within the manufacturing facility—and the dry coating course of can even allow designers to enhance battery efficiency.
The dry electrode coating course of depends on the usage of particular binders that may kind an electrode coating with out being dissolved in a solvent, similar to fluoropolymer binders with Teflon™ from specialty chemical firm Chemours.
To study the benefits of the dry coating course of, and the way firms are assembly the challenges concerned in scaling the know-how up from pilot to manufacturing scale, Charged spoke with Tejas Upasani, World EV Know-how Supervisor at Chemours.
Tejas Upasani: We wish to name Chemours “a startup firm with 200 years of historical past.” We spun out of DuPont in 2015, and we’ve got main manufacturers in varied industries, together with semiconductors and automotive. Beneath our Superior Efficiency Supplies enterprise, we’ve got manufacturers you would possibly acknowledge, similar to Teflon™, Nafion™ and Viton™.
Now we’re experiencing development in our merchandise in a brand-new subject—the dry electrode coating course of—and I’m actually excited to see how Chemours can assist the scale-up of this new utility.
Within the dry course of, most of the components stay the identical—comparable lively supplies, comparable conductive components. What actually adjustments is the binder.
Charged: Are you able to stroll us by way of the fundamental benefits of the dry electrode coating course of versus the normal moist slurry-based course of?
Tejas Upasani: The dry coating course of is a novel approach of producing cathode and anode electrodes in lithium batteries.
Within the conventional moist slurry course of, we’ve got the lively components, we’ve got the conductive components, and we use a selected binder which must be dissolved in a solvent. As soon as all these components are blended collectively, we create what is known as a slurry. That slurry must be coated onto a present collector. At that time, the operate of the solvent is finished, so we dry off the solvent and we get a pleasant coating on the present collector.
Within the dry course of, most of the components stay the identical—comparable lively supplies, comparable conductive components. What actually adjustments is the binder. On this case, we’ll be utilizing superior fluoropolymer binders with Teflon™ which, due to its distinctive properties, doesn’t have to be dissolved in any solvent. It could possibly kind the coating because it goes by way of the processing steps by way of a course of known as fibrillation, which mainly varieties your complete coating on the present collector.
Why is the dry course of advantageous over the moist slurry course of? We will have a look at this from three completely different angles.
One is that it’s rather more environmentally pleasant. The moist slurry course of makes use of NMP [N-Methylpyrrolidone], which is a hazardous solvent. With a view to do away with the solvent within the moist slurry course of, it has to undergo a sequence of ovens. If there isn’t any want for the solvent, then the hazards related to the solvent are eliminated.
The second half is manufacturing prices. When you have a look at how a lot area is required for the moist slurry course of, by some estimates, it’s 10 instances the area in comparison with the dry course of, so there’s an amazing quantity of financial savings of ground area that may be achieved with the dry course of.
The third side is that it allows higher efficiency of the batteries. With the dry course of, we will make thicker electrodes, which may also help with bettering energy density.
Superior fluoropolymer binders from Chemours are actually on the coronary heart and heart of that course of.
Charged: Is that this one thing that might assist to scale back charging instances?
Tejas Upasani: It doubtlessly might. There’s a number of testing that’s being executed proper now, evaluating the moist slurry course of and the dry course of. If you’ll be able to go to a better loading with the dry electrode course of—say, all the way in which to eight or 9 milliamp-hours per sq. centimeter—we will see aggressive or larger charging charges in comparison with a traditional loading of the moist slurry course of, which is about 3 to 4 milliamp-hours per sq. centimeter now. A lot of this work is finished at lab scale or pilot scale, however because the know-how matures and we begin seeing higher course of applied sciences, these could be realized in real-life situations as nicely.
Charged: Is dry electrode coating at the moment in manufacturing?
Tejas Upasani: We’re within the early levels of the event course of. Some {industry} gamers are at manufacturing scale. For instance, on Battery Day in 2020, Tesla introduced that they wished to supply their 4680 cells in a dry electrode course of. And on Investor Day in 2023, the corporate introduced that that they had efficiently carried out business manufacturing of the dry electrode course of. PowerCo, a subsidiary of Volkswagen, has introduced that they’ll deploy and commercialize the dry electrode course of at many various areas. LG Vitality Options has introduced comparable plans.
However because it stands proper now, we’re seeing your complete spectrum—lab, pilot, pre-production, manufacturing—of adoption of the dry electrode course of.
We predict that cell producers and OEMs within the subsequent two to 5 years are going to be in several levels. Some are going to be at pilot scale. Others are going to advance into manufacturing scale. However because it stands proper now, we’re seeing your complete spectrum—lab, pilot, pre-production, manufacturing—of adoption of the dry electrode course of.
Charged: Are there any main technical hurdles that we nonetheless must get previous earlier than this may be extensively adopted?
Tejas Upasani: Actually there are hurdles. All people’s making an attempt to develop the method, they usually’re making an attempt to guarantee that the proper mixing and calendaring could be executed as a way to create a uniform construction. Among the technical hurdles should do with binders and the dry electrode processes enabled by way of understanding the fibril community of PTFE [polytetrafluoroethylene].
The usage of PTFE and the resultant fibril community has been understood for many years, and we, as inventors of PTFE, have invested a number of science behind understanding the fibril community, but it surely usually has been utilized to industries the place PTFE is the dominant part within the utility. For example, for those who have a look at your normal plumber’s tape (Teflon™ tape), it makes use of precisely the identical precept of fibrillation. That’s why you’ll be able to pull it in a single course simply, however within the transverse course, you’ll be able to simply break it aside.
It’s the identical on this utility—we’re making an attempt to regulate the fibrillation by way of the blending course of and thru the calendaring course of. Chemours has invested closely in creating varied kinds of superior fluoropolymer binders with PTFE. These have a variety of various molecular weights and completely different polymer architectures, and all of those are supposed to allow the correct fibrillation traits throughout the electrode course of.
On the cathode aspect, usually PTFE is oxidatively very steady…it’s a really promising utility. On the anode aspect there could be reductive stability challenges related to conventional PTFE, and so utilizing conventional PTFEs won’t be the optimum answer.
Conventional PTFE could have challenges on the anode aspect. On the cathode aspect, usually PTFE is oxidatively very steady. One of many benefits is which you can go to larger voltages and it nonetheless is steady at higher-voltage functions. So, on the cathode aspect, it’s a really promising utility.
On the anode aspect there could be reductive stability challenges related to conventional PTFE, and so utilizing conventional PTFEs won’t be the optimum answer. That’s one of many the reason why we’re creating a number of completely different merchandise and making an attempt to grasp the mechanism of why conventional PTFE just isn’t steady on the anode aspect. And as soon as we perceive that mechanism, how will we resolve that? There’s an amazing quantity of labor happening internally and with our exterior companions as nicely to try to perceive and resolve these hurdles.
Charged: One of many challenges is adhesion. The dry materials has to bond to the electrode floor, however the flat floor and lack of texture could make that troublesome.
Tejas Upasani: The {industry} proper now could be utilizing what we name carbon-coated present collectors. They’ve sure coatings on the present collectors, and when the dry course of movies are made, these get laminated onto that carbon-coated present collector.
That’s the answer that the {industry} has at this level, and it’s working pretty nicely in each anode and cathode processes. Now, if we wished to immediately laminate the movie onto the present collector with none carbon coating, then that’s a bit little bit of an issue, and we’re engaged on it proper now.
We’re ways in which we will alter the chemistry of the polymers themselves as a way to get higher adhesion to the present collectors. If we have been in a position to immediately laminate onto the present collector, why have this carbon coating?
We’re ways in which we will alter the chemistry of the polymers themselves as a way to get higher adhesion to the present collectors. If we have been in a position to immediately laminate onto the present collector, why have this carbon coating? Eliminating the coating reduces the fee. I feel which may come, however proper now the main target is on scaling up the know-how with coated present collectors.
Charged: The method wants to scale back the quantity of binder and different inactive materials to an identical stage as that of moist coating, however this may be costly and exhausting to scale up.
Tejas Upasani: Yeah. Sure cell chemistries require rising the quantity of inactive materials, particularly on the cathode aspect, whereas there are some cell chemistries the place we’re binder loadings of lower than 2%, and in some instances even lower than 1%.
So, it’s already being labored on, making an attempt to scale back the quantity of inactive supplies. It does require a number of course of optimization as a result of, as you’ll be able to think about, the small quantity of binder is holding up your complete powder chemistry. So, a number of course of know-how, together with the fabric enhancements that we’re doing in creating new supplies and developing with completely different polymer chemistries, goes to allow even additional reductions of the quantity of inactive supplies.
Charged: One other problem is uniformity—the dry coating combination must be uniform throughout massive areas of the battery electrodes.
Tejas Upasani: I don’t assume uniformity challenges are essentially restricted to the dry coating course of. There are strategies which were developed within the moist slurry course of to grasp that the viscosity is true or the solids content material is true, and that may assist us to grasp that the uniformity of the slurry can also be good.
As soon as the blending is finished homogeneously, the great thing about the dry electrode course of is that, as soon as it’s laminated onto the present collector, the coating course of is finished. You don’t have any motion or settling of the components.
Within the dry course of, it’s comparable, besides that we’re coping with all of the powders. There are analytical strategies and instruments which are being developed as a way to confirm that these powders are blended appropriately—the lively supplies, carbon black and binders, they have to be blended actually homogeneously. As soon as the blending is finished homogeneously, the great thing about the dry electrode course of is that, as soon as it’s laminated onto the present collector, the coating course of is finished. You don’t have any motion or settling of the components. In a moist slurry course of, for those who have been to make a thick electrode, because the solvent is drying off, these components could begin to settle throughout the drying course of.
Charged: So, your organization would associate with the producer to find out the best combine.
Tejas Upasani: Sure. And all through our historical past, we’ve got checked out utility improvement. That is what we’ve got executed at Chemours for many years. We don’t need to simply say to the shoppers, “Right here’s a fabric, use it.” We don’t need to say that we’re only a provider. We don’t need to cease there. We need to guarantee that we contribute to the success of our prospects as nicely.
There are strategies accessible to grasp the blending homogeneity, that are very R&D-based, and we’re doing a few of that work, but when somebody is doing this on a manufacturing foundation at a producing web site, they don’t seem to be going to have time to take a pattern, go into the R&D lab and look forward to days as a way to get the outcomes. So, after we are creating these strategies internally, we are attempting to develop a technique which goes to be in keeping with manufacturing characterization and evaluation.
Charged: Are you able to inform us about your superior fluoropolymer binders with Teflon PTFE?
Tejas Upasani: Understanding the fibrillation traits is actually the important thing in enabling the dry electrode course of. Now we have a spectrum of various merchandise, which can be found to be utilized in a batch mixing course of, or in a steady mixing course of. Not all of our prospects are going to make use of the very same approach of producing it, so making an attempt to tailor our merchandise to their wants is the important thing.
And provided that we’ve got tried all different types of chemistries for our superior fluoropolymer binder merchandise, it’s simpler for us to grasp what precisely goes to have an effect on the fibrillation traits, and consequently the mechanical properties of those supplies.
Additionally, Chemours is the one fluoropolymer producer who has manufacturing websites in all three main areas—the US, Europe and Asia/Pacific. Once we take into consideration a state of affairs the place the manufacturing goes to be scaled as much as a manufacturing scale, we’ve got the flexibleness of getting the merchandise being made at completely different areas and supporting our prospects with the identical high quality, the identical security requirements and similar requirements utilized to accountable manufacturing.
Charged: We’ve heard about some proposed laws in Europe round PFAS that might influence PTFE. What influence would this have on dry electrode coating?
Tejas Upasani: I’m glad that you just requested the query, as a result of typically it’s the elephant within the room after we are speaking with our {industry} companions.
We at Chemours firmly consider that our fluoropolymers could be manufactured responsibly, and we’re in favor of industry-wide nationwide laws and testing necessities, that are based mostly on science and information—data-driven laws and testing strategies, we’re utterly in favor of that.
We spend a number of time, cash and assets in figuring out the sources of emissions from manufacturing fluoropolymers, and putting in abatement techniques as a way to management these emissions. We’re additionally participating closely in making an attempt to develop alternate manufacturing applied sciences. All of those are steps that we’re taking as a way to meet the wants of potential regulation.
If we have a look at the EU laws, notably, it’s not essentially confined to PTFE. PVDF, which is a fluoropolymer used within the moist slurry course of, is also doubtlessly impacted by the identical laws.
Fluoropolymers usually are important to lithium-ion batteries, they usually’re important for us to transition to a clear power atmosphere. So, we need to be companions within the regulation to guarantee that the laws deal with the considerations, and that these merchandise are manufactured in a accountable approach, and we’re dedicated to doing each issues.
This text first appeared in Situation 69: July-September 2024 – Subscribe now.
