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 just a few 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 large financial savings in price and flooring house within the manufacturing facility—and the dry coating course of also can allow designers to enhance battery efficiency.
The dry electrode coating course of depends on the usage of 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 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 have now main manufacturers in varied industries, together with semiconductors and automotive. Beneath our Superior Efficiency Supplies enterprise, we have now manufacturers you may 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 software.
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 by 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 means of producing cathode and anode electrodes in lithium batteries.
Within the conventional moist slurry course of, we have now the energetic substances, we have now the conductive components, and we use a specific binder which must be dissolved in a solvent. As soon as all these substances are blended collectively, we create what is named 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, 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 possibly type the coating because it goes by the processing steps by a course of referred to as fibrillation, which principally kinds all the 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 far more environmentally pleasant. The moist slurry course of makes use of NMP [N-Methylpyrrolidone], which is a hazardous solvent. In an effort to eliminate the solvent within the moist slurry course of, it has to undergo a sequence of ovens. If there isn’t a want for the solvent, then the hazards related to the solvent are eliminated.
The second half is manufacturing prices. In the event you 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 amazing quantity of financial savings of flooring 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 are able to make thicker electrodes, which can assist 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 would assist to cut back charging instances?
Tejas Upasani: It probably may. There’s a whole lot 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 are able to 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 expertise matures and we begin seeing higher course of applied sciences, these may be realized in real-life eventualities as nicely.
Charged: Is dry electrode coating presently 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 they’d efficiently applied 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 places. LG Vitality Options has introduced related plans.
However because it stands proper now, we’re seeing all the spectrum—lab, pilot, pre-production, manufacturing—of adoption of the dry electrode course of.
We expect 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 all the 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. All people’s attempting to develop the method, and so they’re attempting to make it possible for the right mixing and calendaring may 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 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 whole lot of science behind understanding the fibril community, however it typically has been utilized to industries the place PTFE is the dominant element within the software. For instance, if you happen to 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’ll be able to pull it in a single route simply, however within the transverse route, you’ll be able to simply break it aside.
It’s the identical on this software—we’re attempting to regulate the fibrillation by the blending course of and thru the calendaring course of. Chemours has invested closely in growing varied varieties 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 right fibrillation traits inside the electrode course of.
On the cathode aspect, typically PTFE is oxidatively very secure…it’s a really promising software. On the anode aspect there may be reductive stability challenges related to conventional PTFE, and so utilizing conventional PTFEs may not be the optimum resolution.
Conventional PTFE might have challenges on the anode aspect. On the cathode aspect, typically PTFE is oxidatively very secure. One of many benefits is you can go to greater voltages and it nonetheless is secure at higher-voltage functions. So, on the cathode aspect, it’s a really promising software.
On the anode aspect there may be reductive stability challenges related to conventional PTFE, and so utilizing conventional PTFEs may not be the optimum resolution. That’s one of many the explanation why we’re growing a whole lot of completely different merchandise and attempting to know the mechanism of why conventional PTFE is just not secure on the anode aspect. And as soon as we perceive that mechanism, how will we remedy that? There’s an amazing quantity of labor occurring internally and with our exterior companions as nicely to try 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’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 nicely in each anode and cathode processes. Now, if we needed 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 taking a look at ways in which we are able to alter the chemistry of the polymers themselves as a way to get higher adhesion to the present collectors. If we have been capable of immediately laminate onto the present collector, why have this carbon coating?
We’re taking a look at ways in which we are able to alter the chemistry of the polymers themselves as a way to get higher adhesion to the present collectors. If we have been capable of immediately 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 target 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 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 taking a look at binder loadings of lower than 2%, and in some instances even lower than 1%.
So, it’s already being labored on, attempting to cut back the quantity of inactive supplies. It does require a whole lot of course of optimization as a result of, as you’ll be able to think about, the small quantity of binder is holding up all the powder chemistry. So, a whole lot 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 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 were 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 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 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 are 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, if you happen to have been to make a thick electrode, because the solvent is drying off, these substances might begin to settle throughout the drying course of.
Charged: So, your organization would accomplice with the producer to find out the perfect combine.
Tejas Upasani: Sure. And all through our historical past, we have now checked out software growth. That is what we have now executed 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 make it possible for we contribute to the success of our prospects as nicely.
There are strategies accessible 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 look forward to days as a way to get the outcomes. So, after we are growing these strategies internally, we are attempting to develop a technique which goes to be in step 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. 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 means of producing it, so attempting to tailor our merchandise to their wants is the important thing.
And on condition that we have now tried all different 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 have now the flexibleness of getting the merchandise being made at completely different places 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 rules in Europe round PFAS that would affect PTFE. What affect 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 after we are speaking with our {industry} companions.
We at Chemours firmly imagine 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 a whole lot of time, cash and assets 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 participating 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 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 probably impacted by the identical rules.
Fluoropolymers on the whole are important to lithium-ion batteries, and so they’re important for us to transition to a clear vitality atmosphere. So, we wish to be companions within the regulation to make it possible for the rules handle the considerations, and that these merchandise are manufactured in a accountable means, and we’re dedicated to doing each issues.
This text first appeared in Subject 69: July-September 2024 – Subscribe now.
