The dry electrode coating course of has the potential to allow the manufacturing of higher, greener, cheaper 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 ground house within the manufacturing facility—and the dry coating course of can even 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, resembling 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 know-how up from pilot to manufacturing scale, Charged spoke with Tejas Upasani, World 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’ve main manufacturers in numerous industries, together with semiconductors and automotive. Below our Superior Efficiency Supplies enterprise, we’ve manufacturers you would possibly acknowledge, resembling Teflon™, Nafion™ and Viton™.
Now we’re experiencing progress in our merchandise in a brand-new area—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 substances 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 approach of producing cathode and anode electrodes in lithium batteries.
Within the conventional moist slurry course of, we’ve the lively substances, we’ve the conductive components, and we use a specific binder which must be dissolved in a solvent. As soon as all these substances are combined 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 substances 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 should be dissolved in any solvent. It may possibly type the coating because it goes by the processing steps by a course of referred to as fibrillation, which mainly types your entire 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. With a purpose to do away with the solvent within the moist slurry course of, it has to undergo a sequence 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. When 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 ground house that may be achieved with the dry course of.
The third side is that it allows higher efficiency of the batteries. With the dry course of, we will make thicker electrodes, which may also 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 loads 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 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 greater 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 know-how 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 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 may 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 your entire 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 entire 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 making an attempt to develop the method, they usually’re making an attempt to guarantee that the right mixing and calendaring may be achieved in an effort to create a uniform construction. A number 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, but it surely usually has been utilized to industries the place PTFE is the dominant part within the software. For instance, for those who 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 path simply, however within the transverse path, you possibly can 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 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 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 could be reductive stability challenges related to conventional PTFE, and so utilizing conventional PTFEs won’t be the optimum answer.
Conventional PTFE might have challenges on the anode facet. On the cathode facet, usually PTFE is oxidatively very secure. One of many benefits is you can 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 could be reductive stability challenges related to conventional PTFE, and so utilizing conventional PTFEs won’t be the optimum answer. That’s one of many explanation why we’re growing loads of completely different merchandise and making an attempt to grasp the mechanism of why conventional PTFE just 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 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 needed to instantly 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 will alter the chemistry of the polymers themselves in an effort to get higher adhesion to the present collectors. If we have been capable of 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 in an effort to get higher adhesion to the present collectors. If we have been capable of instantly laminate onto the present collector, why have this carbon coating? Eliminating the coating reduces the associated fee. I believe which 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 an identical stage 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 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, making an attempt to scale 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 your entire powder chemistry. So, loads of course of know-how, together with the fabric enhancements that we’re doing in growing 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 giant areas of the battery electrodes.
Tejas Upasani: I don’t assume 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 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 can be being developed in an effort to confirm that these powders are combined accurately—the lively supplies, carbon black and binders, they should be combined 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, for those who have 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 companion with the producer to find out the best combine.
Tejas Upasani: Sure. And all through our historical past, we’ve checked out software growth. That is what we’ve achieved 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 guarantee that we contribute to the success of our clients as nicely.
There are strategies obtainable 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 website, they aren’t going to have time to take a pattern, go into the R&D lab and look ahead to days in an effort 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 actually 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 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 on condition that we’ve 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. Once we take into consideration a situation the place the manufacturing goes to be scaled as much as a manufacturing scale, we’ve the pliability of getting the merchandise being made at completely different areas 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 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 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 info—data-driven rules and testing strategies, we’re fully in favor of that.
We spend loads of time, cash and sources in figuring out the sources of emissions from manufacturing fluoropolymers, and putting in abatement techniques in an effort 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 in an effort 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 usually are important to lithium-ion batteries, they usually’re important for us to transition to a clear vitality atmosphere. So, we need to be companions within the regulation to guarantee that the rules tackle 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 Challenge 69: July-September 2024 – Subscribe now.
