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 also 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, corresponding to fluoropolymer binders with Teflon™ from specialty chemical firm Chemours.
To find out about some great benefits of the dry coating course of, and the way firms are assembly the challenges concerned in scaling the expertise up from pilot to manufacturing scale, Charged spoke with Tejas Upasani, World EV Expertise 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. Below our Superior Efficiency Supplies enterprise, we now have manufacturers you would possibly acknowledge, corresponding 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 help the scale-up of this new software.
Within the dry course of, lots 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 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 now have the lively 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 combined collectively, we create what known as a slurry. That slurry needs to 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 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 must be dissolved in any solvent. It could kind the coating because it goes by the processing steps by a course of known as fibrillation, which principally 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 totally 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. So as 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. If you happen to have a look at how a lot area is required for the moist slurry course of, by some estimates, it’s 10 occasions the area in comparison with the dry course of, so there’s an amazing quantity of financial savings of flooring area that may be achieved with the dry course of.
The third facet is that it allows higher efficiency of the batteries. With the dry course of, we are able to make thicker electrodes, which may also 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 would assist to cut back charging occasions?
Tejas Upasani: It probably may. There’s a variety of testing that’s being accomplished 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 could be realized in real-life situations as properly.
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 needed to provide their 4680 cells in a dry electrode course of. And on Investor Day in 2023, the corporate introduced that they’d efficiently carried out business 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 places. LG Vitality Options has introduced related 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 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 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: Definitely there are hurdles. Everyone’s making an attempt to develop the method, they usually’re making an attempt to guarantee that the proper mixing and calendaring could be accomplished so as 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].
The usage of PTFE and the resultant fibril community has been understood for many years, and we, as inventors of PTFE, have invested a variety of science behind understanding the fibril community, but it surely typically has been utilized to industries the place PTFE is the dominant element within the software. For instance, if you happen to have 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 path simply, however within the transverse path, you’ll be able to simply break it aside.
It’s the identical on this software—we’re making an attempt to manage the fibrillation by the blending course of and thru the calendaring course of. Chemours has invested closely in growing varied sorts of superior fluoropolymer binders with PTFE. These have a spread of various molecular weights and totally different polymer architectures, and all of those are meant to allow the correct fibrillation traits inside the electrode course of.
On the cathode facet, typically PTFE is oxidatively very secure…it’s a really promising software. On the anode facet there is perhaps 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 facet. On the cathode facet, typically PTFE is oxidatively very secure. One of many benefits is which you could go to greater voltages and it nonetheless is secure at higher-voltage purposes. So, on the cathode facet, it’s a really promising software.
On the anode facet there is perhaps reductive stability challenges related to conventional PTFE, and so utilizing conventional PTFEs may not be the optimum answer. That’s one of many the reason why we’re growing a variety of totally 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 resolve that? There’s an amazing quantity of labor occurring internally and with our exterior companions as properly 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 properly 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 just a little 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 so as to get higher adhesion to the present collectors. If we have been capable of straight 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 so as to get higher adhesion to the present collectors. If we have been capable of straight 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 expertise with coated present collectors.
Charged: The method wants to cut back the quantity of binder and different inactive materials to an analogous degree as that of moist coating, however this may be costly and laborious to scale up.
Tejas Upasani: Yeah. Sure cell chemistries require growing the quantity of inactive materials, particularly on the cathode facet, 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, making an attempt to cut back the quantity of inactive supplies. It does require a variety 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 variety of course of expertise, together with the fabric enhancements that we’re doing in growing new supplies and arising with totally 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 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 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 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 are being developed so as to confirm that these powders are combined appropriately—the lively supplies, carbon black and binders, they must be combined 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 elements. In a moist slurry course of, if you happen to have been to make a thick electrode, because the solvent is drying off, these elements 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 best combine.
Tejas Upasani: Sure. And all through our historical past, we now have checked out software growth. That is what we now have accomplished 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 guarantee that 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 don’t seem to be going to have time to take a pattern, go into the R&D lab and look forward to days so as to get the outcomes. So, once we are growing these strategies internally, we try to develop a way which goes to be according to 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 absolutely 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 clients are going to make use of the very same means of producing it, so making an attempt to tailor our merchandise to their wants is the important thing.
And on condition that we now have 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. 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 totally 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 laws in Europe round PFAS that would affect PTFE. What affect 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 once 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 primarily based on science and info—data-driven laws and testing strategies, we’re utterly in favor of that.
We spend a variety of time, cash and assets in figuring out the sources of emissions from manufacturing fluoropolymers, and putting in abatement techniques so as 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 so as to meet the wants of potential regulation.
If we have a look at the EU laws, 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 laws.
Fluoropolymers generally are important to lithium-ion batteries, they usually’re important for us to transition to a clear power atmosphere. So, we wish to be companions within the regulation to guarantee that the laws tackle 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 Difficulty 69: July-September 2024 – Subscribe now.
