The dry electrode coating course of has the potential to allow the manufacturing of higher, greener, cheaper 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 using hazardous, environmentally dangerous solvents. Taking the solvents out of the method can translate to large financial savings in price and ground house 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 using particular binders that may kind an electrode coating with out being dissolved in a solvent, comparable to fluoropolymer binders with Teflon™ from specialty chemical firm Chemours.
To study some great benefits of the dry coating course of, and the way corporations are assembly the challenges concerned in scaling the know-how up from pilot to manufacturing scale, Charged spoke with Tejas Upasani, International 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 now have main manufacturers in numerous industries, together with semiconductors and automotive. Beneath our Superior Efficiency Supplies enterprise, we now have manufacturers you may acknowledge, comparable to Teflon™, Nafion™ and Viton™.
Now we’re experiencing progress 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 elements stay the identical—related lively supplies, related conductive components. What actually modifications is the binder.
Charged: Are you able to stroll us by means of the fundamental benefits of the dry electrode coating course of versus the standard 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 now have the lively elements, we now have the conductive components, and we use a specific binder which must be dissolved in a solvent. As soon as all these elements are combined collectively, we create what is named a slurry. That slurry needs to be coated onto a present collector. At that time, the operate of the solvent is completed, so we dry off the solvent and we get a pleasant coating on the present collector.
Within the dry course of, most of the elements stay the identical—related lively supplies, related conductive components. What actually modifications 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 will possibly kind the coating because it goes by means of the processing steps by means of a course of referred to as fibrillation, which mainly varieties your entire coating on the present collector.
Why is the dry course of advantageous over the moist slurry course of? We are able to take a look at this from three completely different angles.
One is that it’s far more environmentally pleasant. The moist slurry course of makes use of NMP [N-Methylpyrrolidone], which is a hazardous solvent. As a way to eliminate the solvent within the moist slurry course of, it has to undergo a sequence of ovens. If there is no such thing as a want for the solvent, then the hazards related to the solvent are eliminated.
The second half is manufacturing prices. If you happen to take a look at how a lot house is required for the moist slurry course of, by some estimates, it’s 10 instances the house in comparison with the dry course of, so there’s an incredible quantity of financial savings of ground house that may be achieved with the dry course of.
The third side is that it permits higher efficiency of the batteries. With the dry course of, we will make thicker electrodes, which might help with bettering energy density.
Superior fluoropolymer binders from Chemours are actually on the coronary heart and middle of that course of.
Charged: Is that this one thing that might assist to scale back charging instances?
Tejas Upasani: It doubtlessly may. There’s plenty of testing that’s being achieved proper now, evaluating the moist slurry course of and the dry course of. If you’ll be able to go to the next loading with the dry electrode course of—say, all the best way 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 completed at lab scale or pilot scale, however because the know-how matures and we begin seeing higher course of applied sciences, these will be realized in real-life eventualities as properly.
Charged: Is dry electrode coating at the moment in manufacturing?
Tejas Upasani: We’re within the early phases 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 they’d efficiently applied industrial manufacturing of the dry electrode course of. PowerCo, a subsidiary of Volkswagen, has introduced that they are going to deploy and commercialize the dry electrode course of at many various areas. LG Vitality Options has introduced related plans.
However because it stands proper now, we’re seeing your entire 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 phases. 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 entire spectrum—lab, pilot, pre-production, manufacturing—of adoption of the dry electrode course of.
Charged: Are there any main technical hurdles that we nonetheless have to get previous earlier than this may be broadly adopted?
Tejas Upasani: Definitely there are hurdles. Everyone’s attempting to develop the method, and so they’re attempting to make it possible for the right mixing and calendaring will be achieved in an effort to create a uniform construction. A few of the technical hurdles need to do with binders and the dry electrode processes enabled by means 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 plenty of science behind understanding the fibril community, but it surely typically has been utilized to industries the place PTFE is the dominant part within the utility. For instance, in case you take a look at your commonplace plumber’s tape (Teflon™ tape), it makes use of precisely the identical precept of fibrillation. That’s why you possibly can pull it in a single path simply, however within the transverse path, you possibly can simply break it aside.
It’s the identical on this utility—we’re attempting to manage the fibrillation by means of the blending course of and thru the calendaring course of. Chemours has invested closely in growing numerous forms of superior fluoropolymer binders with PTFE. These have a variety of various molecular weights and completely different polymer architectures, and all of those are meant to allow the correct fibrillation traits inside the electrode course of.
On the cathode aspect, typically PTFE is oxidatively very secure…it’s a really promising utility. On the anode aspect there is likely to be reductive stability challenges related to conventional PTFE, and so utilizing conventional PTFEs won’t be the optimum resolution.
Conventional PTFE could have challenges on the anode aspect. On the cathode aspect, typically PTFE is oxidatively very secure. One of many benefits is that you could go to larger voltages and it nonetheless is secure at higher-voltage functions. So, on the cathode aspect, it’s a really promising utility.
On the anode aspect there is likely to be reductive stability challenges related to conventional PTFE, and so utilizing conventional PTFEs won’t be the optimum resolution. That’s one of many explanation why we’re growing plenty of completely different merchandise and attempting to know the mechanism of why conventional PTFE isn’t secure on the anode aspect. And as soon as we perceive that mechanism, how can we remedy that? There’s an incredible quantity of labor happening internally and with our exterior companions as properly to attempt to perceive and remedy 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 properly in each anode and cathode processes. Now, if we wished to instantly laminate the movie onto the present collector with none carbon coating, then that’s somewhat 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 in an effort to get higher adhesion to the present collectors. If we had been in a position to instantly laminate onto the present collector, why have this carbon coating?
We’re ways in which we will alter the chemistry of the polymers themselves in an effort to get higher adhesion to the present collectors. If we had been in a position to instantly laminate onto the present collector, why have this carbon coating? Eliminating the coating reduces the price. I believe 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 degree as that of moist coating, however this may be costly and exhausting to scale up.
Tejas Upasani: Yeah. Sure cell chemistries require growing 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 circumstances even lower than 1%.
So, it’s already being labored on, attempting to scale back the quantity of inactive supplies. It does require plenty of course of optimization as a result of, as you possibly can think about, the small quantity of binder is holding up your entire powder chemistry. So, plenty of course of know-how, together with the fabric enhancements that we’re doing in growing new supplies and arising 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 suppose uniformity challenges are essentially restricted to the dry coating course of. There are strategies which have been developed within the moist slurry course of to know that the viscosity is true or the solids content material is true, and that can assist us to know that the uniformity of the slurry can be good.
As soon as the blending is completed 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 completed. You don’t have any motion or settling of the elements.
Within the dry course of, it’s related, besides that we’re coping with all of the powders. There are analytical strategies and instruments which might be being developed in an effort to confirm that these powders are combined appropriately—the lively supplies, carbon black and binders, they have to be combined actually homogeneously. As soon as the blending is completed 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 completed. You don’t have any motion or settling of the elements. In a moist slurry course of, in case you had been to make a thick electrode, because the solvent is drying off, these elements could begin to settle in the course of the drying course of.
Charged: So, your organization would companion with the producer to find out the perfect combine.
Tejas Upasani: Sure. And all through our historical past, we now have checked out utility growth. That is what we now have achieved at Chemours for many years. We don’t need to simply say to the purchasers, “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 make it possible for we contribute to the success of our clients as properly.
There are strategies obtainable to know 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 aren’t going to have time to take a pattern, go into the R&D lab and anticipate days in an effort to get the outcomes. So, once we are growing 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 de facto the important thing in enabling the dry electrode course of. We have now 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 clients are going to make use of the very same approach of producing it, so attempting to tailor our merchandise to their wants is the important thing.
And on condition that we now have tried all differing types of chemistries for our superior fluoropolymer binder merchandise, it’s simpler for us to know 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. After we take into consideration a state of affairs the place the manufacturing goes to be scaled as much as a manufacturing scale, we now have the flexibleness of getting the merchandise being made at completely different areas and supporting our clients 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 simply requested the query, as a result of generally it’s the elephant within the room once we are speaking with our {industry} companions.
We at Chemours firmly imagine that our fluoropolymers will be manufactured responsibly, and we’re in favor of industry-wide nationwide laws and testing necessities, that are based mostly on science and details—data-driven laws and testing strategies, we’re fully in favor of that.
We spend plenty of time, cash and assets in figuring out the sources of emissions from manufacturing fluoropolymers, and putting in abatement methods in an effort to management these emissions. We’re additionally partaking closely in attempting to develop alternate manufacturing applied sciences. All of those are steps that we’re taking in an effort to meet the wants of potential regulation.
If we take 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, may be doubtlessly impacted by the identical laws.
Fluoropolymers on the whole are important to lithium-ion batteries, and so they’re important for us to transition to a clear power surroundings. So, we need to be companions within the regulation to make it possible for the laws deal with the issues, and that these merchandise are manufactured in a accountable approach, and we’re dedicated to doing each issues.
This text first appeared in Challenge 69: July-September 2024 – Subscribe now.
