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 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 huge financial savings in value and flooring area within the manufacturing unit—and the dry coating course of may allow designers to enhance battery efficiency.
The dry electrode coating course of depends on using particular binders that may type an electrode coating with out being dissolved in a solvent, similar to fluoropolymer binders with Teflon™ from specialty chemical firm Chemours.
To find out about 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, 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 now we have main manufacturers in varied industries, together with semiconductors and automotive. Beneath our Superior Efficiency Supplies enterprise, now we have manufacturers you would possibly acknowledge, similar 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 help the scale-up of this new utility.
Within the dry course of, lots of the substances stay the identical—related energetic supplies, related conductive components. What actually adjustments is the binder.
Charged: Are you able to stroll us via 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, now we have the energetic substances, now we have the conductive components, and we use a selected binder which must be dissolved in a solvent. As soon as all these substances are blended collectively, we create what is known as 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, lots of the substances stay the identical—related energetic supplies, related 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 will probably type the coating because it goes via the processing steps via a course of referred to as fibrillation, which principally types the complete coating on the present collector.
Why is the dry course of advantageous over the moist slurry course of? We are able to have a look at this from three completely different angles.
One is that it’s way 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 collection 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. In the event 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 incredible quantity of financial savings of flooring area 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 enhancing 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 probably may. There’s quite a lot 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 way in which to eight or 9 milliamp-hours per sq. centimeter—we will see aggressive or greater 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 may be realized in real-life eventualities 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 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 industrial 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 Power Options has introduced related plans.
However because it stands proper now, we’re seeing the 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 numerous 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 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. Everyone’s attempting to develop the method, they usually’re attempting to be sure that the proper mixing and calendaring may be achieved as a way to create a uniform construction. A few of the technical hurdles should do with binders and the dry electrode processes enabled via 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 quite a lot of science behind understanding the fibril community, but it surely usually has been utilized to industries the place PTFE is the dominant element within the utility. For example, in the event you have a look at your customary plumber’s tape (Teflon™ tape), it makes use of precisely the identical precept of fibrillation. That’s why you may pull it in a single course simply, however within the transverse course, you may simply break it aside.
It’s the identical on this utility—we’re attempting to manage the fibrillation via the blending course of and thru the calendaring course of. Chemours has invested closely in growing varied forms of superior fluoropolymer binders with PTFE. These have a spread 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 secure…it’s a really promising utility. On the anode aspect there may be reductive stability challenges related to conventional PTFE, and so utilizing conventional PTFEs may not be the optimum answer.
Conventional PTFE might have challenges on the anode aspect. On the cathode aspect, usually PTFE is oxidatively very secure. One of many benefits is which you can go to greater voltages and it nonetheless is secure at higher-voltage purposes. So, on the cathode aspect, it’s a really promising utility.
On the anode aspect there may be reductive stability challenges related to conventional PTFE, and so utilizing conventional PTFEs may not be the optimum answer. That’s one of many the explanation why we’re growing quite a lot of completely different merchandise and attempting to grasp the mechanism of why conventional PTFE shouldn’t be secure on the anode aspect. And as soon as we perceive that mechanism, how will we clear up that? There’s an incredible quantity of labor happening 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 troublesome.
Tejas Upasani: The {industry} proper now’s 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 straight 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 taking a look at 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 had been capable of straight laminate onto the present collector, why have this carbon coating?
We’re taking a look at 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 had been capable of straight laminate onto the present collector, why have this carbon coating? Eliminating the coating reduces the price. I feel that may come, however proper now the main focus 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 the same stage as that of moist coating, however this may be costly and onerous 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 taking a look at 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 quite a lot of course of optimization as a result of, as you may think about, the small quantity of binder is holding up the complete powder chemistry. So, quite a lot of course of know-how, 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 were developed within the moist slurry course of to grasp that the viscosity is correct or the solids content material is correct, and that may assist us to grasp that the uniformity of the slurry can 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 substances.
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 can be being developed as a way to confirm that these powders are blended accurately—the energetic supplies, carbon black and binders, they have to 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 substances. In a moist slurry course of, in the event you had been to make a thick electrode, because the solvent is drying off, these substances might begin to settle in the course of 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, now we have checked out utility improvement. That is what now we have achieved at Chemours for many years. We don’t wish to simply say to the shoppers, “Right here’s a fabric, use it.” We don’t wish to say that we’re only a provider. We don’t wish to cease there. We wish to be sure that we contribute to the success of our prospects as effectively.
There are strategies out there 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 anticipate days as a way to get the outcomes. So, after we are growing these strategies internally, we try 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 admittedly the important thing in enabling the dry electrode course of. We’ve 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 attempting to tailor our merchandise to their wants is the important thing.
And on condition that now we have 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. After we take into consideration a state of affairs the place the manufacturing goes to be scaled as much as a manufacturing scale, now we have the pliability of getting the merchandise being made at completely different areas and supporting our prospects 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 consider that our fluoropolymers may 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 fully in favor of that.
We spend quite a lot of time, cash and sources in figuring out the sources of emissions from manufacturing fluoropolymers, and putting in abatement programs as a way 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 as a way to meet the wants of potential regulation.
If we have a look at the EU rules, significantly, it’s not essentially confined to PTFE. PVDF, which is a fluoropolymer used within the moist slurry course of, may be probably impacted by the identical rules.
Fluoropolymers basically are important to lithium-ion batteries, they usually’re important for us to transition to a clear vitality atmosphere. So, we wish to be companions within the regulation to be sure 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 Situation 69: July-September 2024 – Subscribe now.
