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 just a few 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 price 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 using particular binders that may type an electrode coating with out being dissolved in a solvent, equivalent to fluoropolymer binders with Teflon™ from specialty chemical firm Chemours.
To study 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 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. Beneath our Superior Efficiency Supplies enterprise, we have now manufacturers you may acknowledge, equivalent to 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 assist the scale-up of this new utility.
Within the dry course of, most of the substances stay the identical—related lively 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 normal 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 lively 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 combined collectively, we create what known as a slurry. That slurry needs to 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 adjustments 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 actually type the coating because it goes by the processing steps by a course of referred to as fibrillation, which mainly types the complete 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. As a way to do away with the solvent within the moist slurry course of, it has to undergo a sequence 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 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 facet is that it allows higher efficiency of the batteries. With the dry course of, we will make thicker electrodes, which will help with enhancing 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 doubtlessly might. There’s lots of 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 the next 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 larger 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 expertise matures and we begin seeing higher course of applied sciences, these could be realized in real-life situations 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 are going to 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 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 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 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, they usually’re attempting to ensure that the proper mixing and calendaring could be completed 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].
The usage of PTFE and the resultant fibril community has been understood for many years, and we, as inventors of PTFE, have invested lots of science behind understanding the fibril community, however it typically has been utilized to industries the place PTFE is the dominant element within the utility. For instance, for those who take 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 regulate the fibrillation by the blending course of and thru the calendaring course of. Chemours has invested closely in creating numerous 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 facet, typically PTFE is oxidatively very secure…it’s a really promising utility. On the anode facet there is likely to be reductive stability challenges related to conventional PTFE, and so utilizing conventional PTFEs won’t be the optimum resolution.
Conventional PTFE could have challenges on the anode facet. On the cathode facet, typically PTFE is oxidatively very secure. One of many benefits is that you would be able to go to larger voltages and it nonetheless is secure at higher-voltage purposes. So, on the cathode facet, it’s a really promising utility.
On the anode facet there is likely to be reductive stability challenges related to conventional PTFE, and so utilizing conventional PTFEs won’t be the optimum resolution. That’s one of many the reason why we’re creating lots of completely different merchandise and attempting 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 remedy that? There’s an amazing quantity of labor occurring internally and with our exterior companions as effectively 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 tough.
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 immediately 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 will alter the chemistry of the polymers themselves in an effort to get higher adhesion to the present collectors. If we had been in a position to immediately 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 had been in a position to immediately laminate onto the present collector, why have this carbon coating? Eliminating the coating reduces the fee. I believe 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 the same degree as that of moist coating, however this may be costly and arduous 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 instances even lower than 1%.
So, it’s already being labored on, attempting to cut back the quantity of inactive supplies. It does require lots 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, lots of 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 may assist us to know that the uniformity of the slurry can 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 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 might be being developed in an effort to confirm that these powders are combined accurately—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 substances. In a moist slurry course of, for those who had been to make a thick electrode, because the solvent is drying off, these substances could begin to settle through the drying course of.
Charged: So, your organization would accomplice with the producer to find out the best combine.
Tejas Upasani: Sure. And all through our historical past, we have now checked out utility growth. That is what we have now completed at Chemours for many years. We don’t wish to simply say to the purchasers, “Right here’s a cloth, use it.” We don’t wish to say that we’re only a provider. We don’t wish to cease there. We wish to ensure that we contribute to the success of our prospects as effectively.
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 aren’t going to have time to take a pattern, go into the R&D lab and watch for days in an effort to get the outcomes. So, once we are creating these strategies internally, we try to develop a way 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 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 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 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 flexibleness of getting the merchandise being made at completely different areas 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 laws in Europe round PFAS that would influence PTFE. What influence would this have on dry electrode coating?
Tejas Upasani: I’m glad that you simply requested the query, as a result of typically it’s the elephant within the room once we are speaking with our {industry} companions.
We at Chemours firmly imagine 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 fully in favor of that.
We spend lots of time, cash and assets in figuring out the sources of emissions from manufacturing fluoropolymers, and putting in abatement programs in an effort 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 in an effort to meet the wants of potential regulation.
If we take a look at the EU laws, 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 laws.
Fluoropolymers on the whole are important to lithium-ion batteries, they usually’re important for us to transition to a clear vitality setting. So, we wish to be companions within the regulation to ensure 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.
