The dry electrode coating course of has the potential to allow the manufacturing of higher, greener, less expensive batteries. It depends on superior fluoropolymer binders with Teflon™
For a couple 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 value and flooring house within the manufacturing facility—and the dry coating course of may 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, equivalent to fluoropolymer binders with Teflon™ from specialty chemical firm Chemours.
To study the benefits of the dry coating course of, and the way corporations are assembly the challenges concerned in scaling the expertise up from pilot to manufacturing scale, Charged spoke with Tejas Upasani, International EV Know-how Supervisor at Chemours.
Tejas Upasani: We prefer 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 varied industries, together with semiconductors and automotive. Underneath our Superior Efficiency Supplies enterprise, we now have manufacturers you may acknowledge, equivalent to Teflon™, Nafion™ and Viton™.
Now we’re experiencing progress in our merchandise in a brand-new discipline—the dry electrode coating course of—and I’m actually excited to see how Chemours can help the scale-up of this new software.
Within the dry course of, most of the elements stay the identical—comparable energetic supplies, comparable conductive components. What actually adjustments is the binder.
Charged: Are you able to stroll us by the essential 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 now have the energetic elements, we now have the conductive components, and we use a selected binder which must be dissolved in a solvent. As soon as all these elements are blended collectively, we create what is named a slurry. That slurry must be coated onto a present collector. At that time, the perform 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 elements stay the identical—comparable energetic 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 should be dissolved in any solvent. It will possibly kind the coating because it goes by the processing steps by a course of known as fibrillation, which principally kinds the whole coating on the present collector.
Why is the dry course of advantageous over the moist slurry course of? We will take 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. To be able to do away with the solvent within the moist slurry course of, it has to undergo a collection 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 take a look at how a lot house is required for the moist slurry course of, by some estimates, it’s 10 occasions the house in comparison with the dry course of, so there’s an incredible quantity of financial savings of flooring house that may be achieved with the dry course of.
The third facet 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 heart of that course of.
Charged: Is that this one thing that might assist to cut back charging occasions?
Tejas Upasani: It doubtlessly may. There’s loads of testing that’s being carried out 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 increased charging charges in comparison with a standard 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 expertise matures and we begin seeing higher course of applied sciences, these could be realized in real-life situations as effectively.
Charged: Is dry electrode coating at present 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 needed to provide their 4680 cells in a dry electrode course of. And on Investor Day in 2023, the corporate introduced that that they had efficiently applied 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 alternative places. LG Vitality Options has introduced comparable plans.
However because it stands proper now, we’re seeing the whole 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 the whole 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 broadly adopted?
Tejas Upasani: Definitely there are hurdles. Everyone’s making an attempt to develop the method, they usually’re making an attempt to ensure that the right mixing and calendaring could be carried out with the intention to create a uniform construction. A few of the technical hurdles must do with binders and the dry electrode processes enabled by understanding the fibril community of PTFE [polytetrafluoroethylene].
Using PTFE and the resultant fibril community has been understood for many years, and we, as inventors of PTFE, have invested loads of science behind understanding the fibril community, nevertheless it usually has been utilized to industries the place PTFE is the dominant part within the software. For example, 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 route simply, however within the transverse route, you possibly can simply break it aside.
It’s the identical on this software—we’re making an attempt to regulate the fibrillation by the blending course of and thru the calendaring course of. Chemours has invested closely in growing 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 right fibrillation traits inside the electrode course of.
On the cathode facet, usually PTFE is oxidatively very secure…it’s a really promising software. On the anode facet 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 facet. On the cathode facet, usually PTFE is oxidatively very secure. One of many benefits is that you would be able to go to increased voltages and it nonetheless is secure at higher-voltage functions. So, on the cathode facet, it’s a really promising software.
On the anode facet 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 the reason why we’re growing loads of completely different merchandise and making an attempt to know the mechanism of why conventional PTFE isn’t secure on the anode facet. And as soon as we perceive that mechanism, how will we clear up that? There’s an incredible quantity of labor occurring internally and with our exterior companions as effectively to try to perceive and clear up 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 tough.
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 effectively in each anode and cathode processes. Now, if we needed to instantly laminate the movie onto the present collector with none carbon coating, then that’s a bit of 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 with the intention to get higher adhesion to the present collectors. If we have 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 with the intention to get higher adhesion to the present collectors. If we have been in a position to instantly laminate onto the present collector, why have this carbon coating? Eliminating the coating reduces the fee. I feel that may come, however proper now the main focus is on scaling up the expertise with coated present collectors.
Charged: The method wants to cut back the quantity of binder and different inactive materials to an identical degree as that of moist coating, however this may be costly and arduous to scale up.
Tejas Upasani: Yeah. Sure cell chemistries require rising the quantity of inactive materials, particularly on the cathode facet, 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, making an attempt to cut back the quantity of inactive supplies. It does require loads of course of optimization as a result of, as you possibly can think about, the small quantity of binder is holding up the whole powder chemistry. So, loads of course of expertise, together with the fabric enhancements that we’re doing in growing 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 giant 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 correct or the solids content material is correct, and that may assist us to know that the uniformity of the slurry can also be good.
As soon as the blending is finished homogeneously, the fantastic 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 elements.
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 might be being developed with the intention to confirm that these powders are blended appropriately—the energetic supplies, carbon black and binders, they should be blended actually homogeneously. As soon as the blending is finished homogeneously, the fantastic 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 elements. In a moist slurry course of, in case you have been to make a thick electrode, because the solvent is drying off, these elements could begin to settle throughout the drying course of.
Charged: So, your organization would associate with the producer to find out the perfect combine.
Tejas Upasani: Sure. And all through our historical past, we now have checked out software growth. That is what we now have carried out 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 ensure that we contribute to the success of our clients as effectively.
There are strategies out there 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 website, they don’t seem to be going to have time to take a pattern, go into the R&D lab and watch for days with the intention to get the outcomes. So, after we are growing these strategies internally, we are attempting to develop a way which goes to be consistent 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 basically the important thing in enabling the dry electrode course of. We now 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 clients 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 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. Once we take into consideration a situation the place the manufacturing goes to be scaled as much as a manufacturing scale, we now have the pliability of getting the merchandise being made at completely different places and supporting our clients with the identical high quality, the identical security requirements and identical requirements utilized to accountable manufacturing.
Charged: We’ve heard about some proposed rules in Europe round PFAS that might impression PTFE. What impression would this have on dry electrode coating?
Tejas Upasani: I’m glad that you just requested the query, as a result of generally it’s the elephant within the room after we are speaking with our {industry} companions.
We at Chemours firmly imagine that our fluoropolymers could be manufactured responsibly, and we’re in favor of industry-wide nationwide rules and testing necessities, that are primarily based on science and information—data-driven rules and testing strategies, we’re utterly in favor of that.
We spend loads of time, cash and assets in figuring out the sources of emissions from manufacturing fluoropolymers, and putting in abatement techniques with the intention to management these emissions. We’re additionally partaking closely in making an attempt to develop alternate manufacturing applied sciences. All of those are steps that we’re taking with the intention to meet the wants of potential regulation.
If we take a look at the EU rules, 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 rules.
Fluoropolymers typically are important to lithium-ion batteries, they usually’re important for us to transition to a clear power setting. So, we need to be companions within the regulation to ensure that the rules 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 Problem 69: July-September 2024 – Subscribe now.
