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 number 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 huge financial savings in value and ground house 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 the usage of particular binders that may type 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 wish to name Chemours “a startup firm with 200 years of historical past.” We spun out of DuPont in 2015, and we’ve got main manufacturers in numerous industries, together with semiconductors and automotive. Below our Superior Efficiency Supplies enterprise, we’ve got manufacturers you would possibly acknowledge, corresponding 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 assist 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 adjustments 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 standard 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’ve got the lively substances, we’ve got the conductive components, and we use a selected 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 operate 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 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 might probably type the coating because it goes by way of the processing steps by way of a course of referred to as fibrillation, which mainly types your 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. To be able to eliminate 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. Should 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 incredible quantity of financial savings of ground 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 will 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 scale back charging instances?
Tejas Upasani: It doubtlessly may. There’s a whole lot 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 a better loading with the dry electrode course of—say, all the best way to eight or 9 milliamp-hours per sq. centimeter—we are able to 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 levels 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 provide 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 are going to deploy and commercialize the dry electrode course of at many various places. LG Power 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 predict that cell producers and OEMs within the subsequent two to 5 years are going to be in numerous 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 have to get previous earlier than this may be broadly adopted?
Tejas Upasani: Actually there are hurdles. All people’s making an attempt to develop the method, they usually’re making an attempt to ensure that the right mixing and calendaring may be completed with the intention to create a uniform construction. A few of the technical hurdles need to do with binders and the dry electrode processes enabled by way of 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 a whole lot of science behind understanding the fibril community, nevertheless it usually has been utilized to industries the place PTFE is the dominant part within the software. For instance, in case 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 may pull it in a single path simply, however within the transverse path, you may simply break it aside.
It’s the identical on this software—we’re making an attempt to regulate 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 spread 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, usually PTFE is oxidatively very steady…it’s a really promising software. On the anode facet there may be reductive stability challenges related to conventional PTFE, and so utilizing conventional PTFEs may not be the optimum resolution.
Conventional PTFE could have challenges on the anode facet. On the cathode facet, usually PTFE is oxidatively very steady. One of many benefits is which you can 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 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 explanation why we’re creating a whole lot of completely different merchandise and making an attempt to grasp 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 remedy that? There’s an incredible quantity of labor occurring internally and with our exterior companions as nicely to attempt 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 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 nicely in each anode and cathode processes. Now, if we wished to straight laminate the movie onto the present collector with none carbon coating, then that’s a bit of little bit of an issue, and we’re engaged on it proper now.
We’re ways in which we are able to alter the chemistry of the polymers themselves with the intention to get higher adhesion to the present collectors. If we have been in a position to straight laminate onto the present collector, why have this carbon coating?
We’re ways in which we are able to alter the chemistry of the polymers themselves with the intention to get higher adhesion to the present collectors. If we have been in a position to straight laminate onto the present collector, why have this carbon coating? Eliminating the coating reduces the associated fee. 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 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 rising the quantity of inactive materials, particularly on the cathode facet, whereas there are some cell chemistries the place we’re 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 scale back the quantity of inactive supplies. It does require a whole lot of course of optimization as a result of, as you may think about, the small quantity of binder is holding up your complete powder chemistry. So, a whole lot 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 were developed within the moist slurry course of to grasp that the viscosity is true or the solids content material is true, and that may assist us to grasp that the uniformity of the slurry can also 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 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 with the intention 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 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 substances. In a moist slurry course of, in case you have been to make a thick electrode, because the solvent is drying off, these substances could begin to settle throughout 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’ve got checked out software growth. That is what we’ve got 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 clients as nicely.
There are strategies out there 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 don’t seem to be going to have time to take a pattern, go into the R&D lab and watch for days with the intention to get the outcomes. So, once we are creating these strategies internally, we are attempting 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. 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 method of producing it, so making an attempt to tailor our merchandise to their wants is the important thing.
And provided that we’ve got tried all differing 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 got the flexibleness of getting the merchandise being made at completely 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 impression PTFE. What impression 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 imagine that our fluoropolymers may be manufactured responsibly, and we’re in favor of industry-wide nationwide laws and testing necessities, that are primarily based on science and details—data-driven laws and testing strategies, we’re fully in favor of that.
We spend a whole lot of time, cash and sources in figuring out the sources of emissions from manufacturing fluoropolymers, and putting in abatement techniques with the intention 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 with the intention to meet the wants of potential regulation.
If we take 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, 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 power atmosphere. So, we wish to be companions within the regulation to ensure that the laws handle 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 Concern 69: July-September 2024 – Subscribe now.
