Dry Batts (Part 2)
Last year we did a write up on dry electrodes on the tech and the relevant players. Here’s a part two where we cover a bit more of the companies. And because we’re talking about dry electrodes, we have to talk about slurries with our sponsor TA Instruments!
Electrode slurries are gaining prominence as a critical area for battery improvement and innovation, and for good reason. These slurries allow the transfer of lithium ions between electrodes and offer critical opportunities to optimize manufacturing for efficiency, reduced cost, and improved battery performance. Slurry researchers face common challenges: (1) What temperature and speed are best for mixing and coating? (2) How do different additives or particle sizes affect stability and processing? (3) What is the slurry’s shelf life? (4) How can quality control be assessed?
Rheology, the study of the flow and deformation of materials, is a powerful technique for analyzing the viscosity and viscoelasticity performance of battery slurries. As the world leader in advanced rheometers for research and material development, TA Instruments offers resources to help battery developers understand slurry rheology:
Learn how to measure the influence of particle size on battery slurries in this Application Note, and learn how to predict slurry behavior, choose the best materials, and improve manufacturing in this eBook of slurry research examples.
One year ago we wrote a bit about dry electrodes.
As a quick summary, the role of the solvent in batteries is to combine everything into a slurry and make sure the mixtures are homogenous (aka well mixed across the entire pot). In the cathode, NMP is very effective at dissolving the binder and making slurries, which is why it is commonly used in many battery factories. These solvents are transient, meaning they are used in the coating stage but ultimately dried and removed and not in the final coating product.
One year on from our first post about dry electrodes, companies continue to explore new ways to innovate on the manufacturability of battery electrodes. A few highlights:
Auto & battery makers dip more toes in dry electrodes
PowerCo (Volkswagen’s battery arm) is continuing to invest in printing specialist Koenig & Bauer AG to commercialize their version of dry electrodes using roller presses and powder coaters.
Tesla acquired Maxwell in 2019, sold back most of the company in 2021, and continues to put in efforts in dry coatings by hiring experts like Matt Tyler in 2023. Tesla’s tech is based on a PTFE binder.
Vinfast/Toyota/TDK/ATL invested in battery tech startups like AM Batteries.
LG Chem has some indication of working in the space too.
ACC (Automotive Cells Company) is exploring the space too with this job description (this link may not work in the future when the role is filled).
More startups in the scene
AM Batteries (Massachusetts, USA) is a player in the space backed by TDK Ventures. AM Batteries is working on an electro-spray approach, involving a “dry spray of electrically charged cathode particles which are attracted to the oppositely charged base foil”, followed by mechanical pressing and hot rolling.
This Nature paper from Ludwig et al. (+ coauthors Zhangfeng Zheng, Wan Shou, Yan Wang and Heng Pan, most of who now work at AM Batteries) outlines the main technology behind their work. It consists of a powder unit and an electrostatic spray gun to charge fluidized dry particles, which will be attracted to the grounded current collector. Following this, a hot roller is used to fix thickness, density, and porosity, as well as to apply heat to activate the binding material.
Adhesion between the electrode material and the current collector appears to be one of the common issues. The paper from Liu et al (with co-authors also on the AM Batteries team) describes a method of dry-spraying an interfacial “adhesion enhancer” of PVDF.
LiCAP (California, USA) is another company working to commercialise dry battery electrodes and appears to be focusing on the formulation of these electrodes. Core patents include:
Dry electrode manufacture by temperature activation method. This patent describes using a specific solvent to activate the binder, which can evaporate without any drying process. “The binder may be activated to improve its adhesion strength by adding a highly vaporizable solvent as described in the present inventor's patent "Electrode for Energy Storage Devices and Method of Making Same. Examples may be hydrocarbons, low boiling point solvents, acetates, alcohols, glycols, acetone, DMC, ethanol, methanol, DEC, etc.” The mixture can then be heated to >70 deg C to activate the binder.
Dry electrode manufacture with composite binder. The patent covers using a binder comprised of PTFE and some composition of PVDF, PEO, and CMC.
Dry electrode manufacture with lubricated active material mixture. The patent covers the lubrication of the active material mixture that will be pressed into a free-standing film, using a polymer additive with a liquid carrier. The patent notes that the lubricating effect of the polymer additive is found to improve the quality of the resulting free-standing film in the disclosed dry electrode manufacturing process, making it possible to use less binder and thus more active material.
Inition (Oxford, UK) is developing a semisolid process for particle alignment in electrodes, reducing charge transfer resistance and allows for thicker electrodes.
Aetios (Indiana, USA - fka Ocella Tech) worked on thin film coating for micro-batteries for IoT applications, now pivoted to dry coatings. They use a polymer composite radiation curing process.
Intecells (Michigan, USA) is using a cold plasma powder coating (CPC) using a nozzle to “3D print” electrode materials over multiple trips of scanning.
This is relatively similar to Sakuu’s 3D printing tech called Kavian. There are a few ideas on what they’re doing - they print a single jetted fluid material to bind a thin bed of cathode powder particles together. We found Sakuu to use a UV-cured process based on employees’ job profiles. And it also looks like Sakuu prints its ceramic electrolyte, followed by a sintering process. In Nov 2022, Sakuu partnered with LiCAP and Sakuu plans to license LiCAP’s proprietary dry battery electrodes.
Equipment manufacturers
Saueressig Engineering (part of Matthews Engineering). German based company. ”Previous reports have suggested that Saueressig could be involved in making machines for Tesla’s battery cell production lines for Giga Texas and Giga Berlin”. Saueressig is also a partner of Fraunhofer’s dry coating research project.
Dürr Group. Long time electrode coating equipment manufacturer very recently (this month!) joined the dry electrode game, with a partnership with LiCAP.
BW Paper Systems. US based company working on everything from corrugated cardboard, passport-grade paper, and battery electrodes now. Partner to Siemens and OG dry battery electrode startup LiCAP.
Chinese companies with all sorts of battery manufacturing and test equipment: Xiamen Tob (nice videos and images), TMAX, + others.
🔋 Battery Chats: Hieu Duong, Chief Manufacturing Officer at AM Batteries
Hieu Duong is the Chief Manufacturing Officer at AM Batteries. Duong is an interdisciplinary engineer with over 20 years of experience in technology development and industrialization. With a Ph.D. in Chemistry from UCLA, he advanced membrane technologies at GE and led battery innovations at Quallion and Zpower, where he led the development of composite separators to enable robust cycling of silver-zinc rechargeable batteries. At Maxwell Technologies, he developed the Dry Battery Electrode (DBE) process, a move that caught Tesla's attention, leading to an acquisition in 2019. As Tesla's Director of Electrode Engineering, Duong championed the DBE's commercialization. Now, at AM Batteries, he's leading the development and commercialization of low-cost lithium-ion battery manufacturing techniques.
Background: Tell me about your background and what experiences really made you interested in batteries and your career to Maxwell.
My passion is in early-stage technology development and industrialization, especially the transformative ones. I was educated as a synthetic organic chemist whose synthesized molecular targets ranging from bio-active compounds to rigid adamantane based chelates to elusive oligoacene systems. Over my professional career, I’ve expanded into materials science and engineering and manufacturing process technologies. My interest in batteries started with my childhood hobby in radio control cars. Back then, NiCd batteries were horrendously long to charge with terrible runtime and cycle life. Hence, I’ve always been inspired to improve portable power. My entry into batteries started with development programs in membrane and separation technologies, which morphed into composite separator for silver-zinc batteries, high nickel lithium-ion batteries, lithium based batteries and ultimately, dry battery electrode (DBE) manufacturing over a span of 5 companies. I started DBE development in 2011 and helped it grew into commercial scale, a dream outcome for any scientist.
Career: You've had an impressive journey from Maxwell to Tesla, and now at AM Batteries. How have these transitions shaped your perspective on battery technology and its evolution?
My experience really revealed how nascence lithium-ion battery technology and industrialization is in the US. Building gigafactory is easy, getting it to produce giga-watthours profitably is a monumental endeavor. I believe we are in a tectonic shift in energy generation and storage, so to come out a winner, we must be realistic on where we placed our bets. We should appreciate that the simple act of duplicating gigafactories by legacy cell manufacturers is non-trivial. As such, newcomers need to ensure that their products are competitive by selecting manufacturing processes that are sustainably lower cost and strategically accommodative to new inbound chemistries.
Tech: Tell us more about why and how dry coating technologies can transform the battery industry, and what's different about AM Batteries specifically.
Dry battery electrode technology delivers 3 key features: 1. Cost – lower capex & opex. 2. Performance – differentiating cell echem & processing materials that are liquid sensitive. 3. Sustainability – solvent-free & decarbonization. AM Batteries DRY2.0 process captures all three using a proprietary dry powder deposition process to create a highly configurable electrode from commonly used commercially available battery grade materials. The AM Batteries process coats dry free-flowing powder directly onto the current collector, thus this approach broadens our binder chemistry options, widens the electrode loading window, and shortens the overall manufacturing cycle time.
Manufacturing adoption: When it comes to novel chemistries and formulations, nothing is truly "drop in". There is a large amount of re-tooling and re-optimization that needs to be done. How receptive are factories to adopting this new technology?
Converting from wet to dry manufacturing will require re-tooling for existing companies with tremendous benefits in opex cost, afforded by about 80% smaller operation footprint and greater 50% labor and energy cost savings. New factories will reap additional benefits in capex cost savings for launching with dry electrode manufacturing and more importantly, gaining a competitive edge over wet coating process. What production line changes have to happen to dry coat and is that feasible? Converting from wet to dry manufacturing will require swapping out mixers and coater with about 5X increase in production capacity in the existing wet coating footprint. How difficult has it been to source equipment for this? – Not too difficult as our equipment leverages many off-the-shelf components used in wet coating systems. The key component in dry processing equipment is the dry coating unit that replaces the energy intensive slot-die/drying oven/solvent recovery in wet coating system.
Challenges: You announced work on dry battery electrode coatings many years ago at Tesla, but has shown it takes a long time to develop new materials like this.
I don’t think the launch of dry electrode manufacturing could have been done any quicker given its paradigm shift in nature without an established ecosystem. Hence, I feel that its success is quite impressive. Can we think of any transformative battery tech that has developed into large scale commercial products in the last 20 years globally? What are the hardest challenges for you today? – Talent acquisition and not enough hours in a day.
General trends: Based on your experience, what future innovations or trends do you predict will emerge in the battery industry in the next decade?
For any future innovations or trends to be successful, it needs to equate to overall cost savings, dollar per kilowatt hour. The next decade will be heavily cost driven since current chemistries are sufficient to serve many applications. Hence, I don’t think mass adoption in EVs and storage applications is sustainable without cost reduction afforded by process and materials. In addition to cost savings, the selected manufacturing process needs to be future-proof in order to accommodate new chemistries and electrode structures.
🌞 Thanks for reading!
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