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 a couple 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 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, reminiscent of fluoropolymer binders with Teflon™ from specialty chemical firm Chemours.
To study the 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, International EV Expertise 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 have now main manufacturers in numerous industries, together with semiconductors and automotive. Underneath our Superior Efficiency Supplies enterprise, we have now manufacturers you would possibly acknowledge, reminiscent of 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 components stay the identical—related energetic supplies, related conductive components. What actually modifications is the binder.
Charged: Are you able to stroll us by way of the fundamental 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 method of producing cathode and anode electrodes in lithium batteries.
Within the conventional moist slurry course of, we have now the energetic components, we have now the conductive components, and we use a specific binder which must be dissolved in a solvent. As soon as all these components are combined collectively, we create what is known as a slurry. That slurry needs to be coated onto a present collector. At that time, the perform 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 components stay the identical—related energetic 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 should be dissolved in any solvent. It could actually kind the coating because it goes by way of the processing steps by way of a course of known as fibrillation, which mainly types all the 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. To be able to eliminate the solvent within the moist slurry course of, it has to undergo a collection 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. When you take 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 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 might. There’s numerous testing that’s being completed 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 best way 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 completed 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 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 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 alternative places. LG Power 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 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 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 must get previous earlier than this may be broadly adopted?
Tejas Upasani: Actually there are hurdles. All people’s attempting to develop the method, they usually’re attempting to be sure that the proper mixing and calendaring may be completed to be able to create a uniform construction. A number of the technical hurdles should do with binders and the dry electrode processes enabled by way 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 numerous 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, in the event 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 attempting to manage the fibrillation by way of the blending course of and thru the calendaring course of. Chemours has invested closely in creating 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 supposed to allow the correct fibrillation traits throughout the electrode course of.
On the cathode facet, typically PTFE is oxidatively very steady…it’s a really promising software. On the anode facet there could 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 facet. On the cathode facet, typically PTFE is oxidatively very steady. One of many benefits is that you would be able to go to increased voltages and it nonetheless is steady at higher-voltage functions. So, on the cathode facet, it’s a really promising software.
On the anode facet there could be reductive stability challenges related to conventional PTFE, and so utilizing conventional PTFEs may not be the optimum answer. That’s one of many explanation why we’re creating numerous completely different merchandise and attempting to know the mechanism of why conventional PTFE is just not steady on the anode facet. And as soon as we perceive that mechanism, how will we resolve that? There’s an incredible quantity of labor happening internally and with our exterior companions as nicely 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’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 wished to instantly laminate the movie onto the present collector with none carbon coating, then that’s slightly 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 to be able 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 taking a look at ways in which we will alter the chemistry of the polymers themselves to be able 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 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 scale back the quantity of binder and different inactive materials to an analogous stage as that of moist coating, however this may be costly and laborious 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 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 numerous course of optimization as a result of, as you possibly can think about, the small quantity of binder is holding up all the powder chemistry. So, numerous course of expertise, together with the fabric enhancements that we’re doing in creating 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 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 completed. You don’t have any motion or settling of the components.
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 to be able to confirm that these powders are combined accurately—the energetic supplies, carbon black and binders, they should be combined actually homogeneously. As soon as the blending is completed 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 completed. You don’t have any motion or settling of the components. In a moist slurry course of, in the event you had been to make a thick electrode, because the solvent is drying off, these components might 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 have now checked out software growth. That is what we have now completed at Chemours for many years. We don’t need to simply say to the shoppers, “Right here’s a cloth, use it.” We don’t need to say that we’re only a provider. We don’t need to cease there. We need to be sure that we contribute to the success of our prospects as nicely.
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 aren’t going to have time to take a pattern, go into the R&D lab and anticipate days to be able to get the outcomes. So, after we are creating these strategies internally, we try 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’ve got 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 method of producing it, so attempting to tailor our merchandise to their wants is the important thing.
And provided that we have now 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 have now the pliability 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 might influence PTFE. What influence 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 may be manufactured responsibly, and we’re in favor of industry-wide nationwide rules and testing necessities, that are based mostly on science and information—data-driven rules and testing strategies, we’re utterly in favor of that.
We spend numerous time, cash and sources in figuring out the sources of emissions from manufacturing fluoropolymers, and putting in abatement methods to be able 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 to be able to meet the wants of potential regulation.
If we take 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 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 be sure that the rules deal with the considerations, and that these merchandise are manufactured in a accountable method, and we’re dedicated to doing each issues.
This text first appeared in Difficulty 69: July-September 2024 – Subscribe now.
