Transformative Manufacturing in the EV Battery Industry Dry Processing, Coating, Printing to Drive Development in the Near-term

Wet processing of battery electrodes for use in electric vehicles (EVs) has matured as a technology and represents current best practices in terms of performance. The practices are far from “best,” however, in terms of cost, safety, scalability, quality control, and environmental impact. Solvent drying and recovery remain expensive and time-consuming. And, according to an article in the MDPI journal?Energies, drying processes account for 39 percent of the energy required to produce an EV battery. Electrode drying is responsible for about half of that usage.

“Establishing knowledge within the LIB [lithium-ion battery] industry regarding state-of-the-art drying techniques and solvent evaporation mechanisms is vital for optimizing process conditions, detecting alternative solvent systems, and discovering novel techniques,” the authors conclude.

The issue generated lively discussions among the experts gathered for October’s Energy Week presented by?TDK Ventures.?

Arrelaine Dameron, vice president of research and development said her company, Colorado-based Forge Nano, is developing coatings and processes for graphite anode material.?The focus on innovations to reduce capital and operating expenses include dry processing, reducing the process and equipment of formation, and “anything we can implement on the front end of battery production and recycling” she said.?“Let’s set ourselves up to make this energy transition more environmentally friendly than the last one.”

That can be done by developing materials that can be used with minimal downstream or lifetime environmental impact, making manufacturing simpler and equipment easier to maintain, and - exacerbated by the labor restraints imposed by COVID-19 - automating as many processes as possible.

Automation should include printing technologies that will give developers options when it comes to the materials and configurations they use, noted Bob Galyen, founder of Galyen Energy and former chief technology officer for CATL.

“Both the active material and the electrode matrix can be printed, and printing can apply 3 to 5 times the coating thickness possible through mixing and other means,” he said. “Different types of active materials can be printed on a single electrode, compared to mixing processes. That enables the 3-D printing of odd shapes, varying thickness, varying substrate, and varying densities of layers.”

He explained that printing, which works for both liquid and solid-state materials, can place materials in layers, with varying compounds and materials used in each stratum.

Yan Wang, an engineering professor at Worcester Polytechnic Institute and co-founder of?Battery Resourcers?(a battery recycling company) and?AM Batteries (a startup working on dry electrode processing), said he has been researching and affiliating with companies focused on developing recycling and dry manufacturing for 10 years. There was a time, he said, when it was not uncommon for only three to five people to show up for an ECS conference presentation. He became interested in dry manufacturing following a discussion with an A123 Systems official several years ago. The drying process, he learned, created a significant bottleneck.

Battery anodes materials and other assemblies are hydrophilic, absorbing moisture during shipping/handling and soaking up water during manufacturing that must be removed before final assembly. At the time, Wang said, this was accomplished by placing the components in vacuum ovens, but these methods had limited effectiveness. They could only be used at relatively low temperatures to avoid damaging the sensitive polymers and other materials composing the batteries.?

A?report?from Oak Ridge National Laboratory concluded that removing the moisture that is taken up by electrodes during shipment and other manufacturing steps before assembly can commence presents an “operational bottleneck”?

Still, even low moisture content can reduce a cell’s lifespan and power capacity. So, it was worthwhile to investigate ways to remove as much as possible, Wang noted. Dry manufacturing and coating printing offer a way to keep water from forming in and on the components so manufacturers can save time and money that otherwise would have to be invested in drying.?

Dipender Saluja, managing director of Palo Alto, Calif.-based Capricorn Investment Group, said that while academic and engineering interest in dry batteries has picked up over the last decade, investor interest has been slow to follow. Even with such promising companies as Tesla and Maxwell Technologies (which Tesla acquired in 2019 and divested in 2021 after absorbing its dry cell processing technology) involved in the development of dry electrodes, venture capital has not yet flooded in. Anil Achyuta, TDK Ventures investment director, said the few companies working hard to produce viable dry electrode products are interested in their potential not only for use in the lithium-ion batteries that power their current vehicles under production but also for future products powered by solid-state batteries.

Industry and academia are working to develop energy boost, solvent reduction, and other alternatives to wet electrodes processing.?The challenge?often boils down to building an electrode coating that is thick enough to improve performance and possesses a stable pore structure to allow rapid enough ion diffusion.

Tesla intends to implement the insights it gained from its?Maxwell?ownership to improve discharge rates that can be scaled to existing and developing high energy density battery chemistries and anode materials to generate 500-plus watt-hours per kilogram

Maxwell claims that its dry battery electrode (DBE) coating technology can be used with “classical and advanced” lithium-ion battery chemistries, but “unlike conventional slurry cast wet coated electrode, Maxwell’s DBE produces a thick electrode that allows for high energy density cells with better discharge rate capability than those of a wet coated electrode.”?

Dry pressing?offers another avenue for accomplishing the same goal. This technology seeks to manufacture LIB electrodes exclusively from active battery materials and conductive binders and additives. Dry pressing uses holey graphene (hG) to introduce a nanoporous compressibility characteristic to otherwise incompressible anode and cathode powders to encourage the expulsion of trapped gases.

Others are leveraging the capabilities of dry film to replace binder-heavy slurries with a synthetic polymer (PTFE) binder, insulator, and premature discharge safeguard.?Proponents say?the process has proven suitable for use in sulfide and high-electrode-loading applications.?

“Regardless of what tech we end up with - even lithium-ion batteries will benefit from improvements in manufacturing - there is lots of room to improve the carbon footprints left by existing technology,” according to Shirley Meng, Energy Week panelist and professor of nanoengineering and materials science at the University of California San Diego. “The process can be simplified and made more energy-efficient and sustainable because LIB tech is here to stay and even moving to other chemistries.”

Sara Chamberlain, who co-founded and manages Chicago-based Energy Foundry, said her early-stage cleantech venture firm is already investing in startups focused on inventing new battery component materials rather than enhancing, developing, and finding applications for existing media.

Wang said industry and academia have merged theory and buildability over the last 20 to 30 years to improve materials science. As a result, the cost of batteries has decreased by 25 percent.

“Still, the different manufacturing steps are very resource-consuming,” he said. “Manufacturers do not just enable lower cost and carbon consumption, but they also can contribute to the production of better batteries.”

Innovative companies continue to develop the technology that will enable manufacturers to further reduce carbon their carbon footprints, drive down battery manufacturing cost, and achieve the energy density and other performance metrics. Technologies like dry electrode processing, coating, and 3D electrode printing are positioned to drive more efficient, marketable processes for battery manufacturing.

TDK Ventures invests in technologies and solutions that embrace digital, energy, and environmental transformations. The venture fund focuses on seed-stage to B-round startups that leverage fundamental material science to unlock a sustainable future.