Guest Editor article by Cesar Hernandez, Demand Creation Energy Lead, and Richard Kay, Segment Leader, Manufacturing and Processing – EMEAI, at Sherwin-Williams Protective and Marine.
As the world transitions to emobility, we are witnessing the birth of a whole new industry, EV battery manufacturing, complete with its own unique challenges and solutions.
EV battery plants are just one part of this evolution. And with no well-established blueprint for construction, manufacturers have, to date, had little evidence-based guidance. Now, new data on the effectiveness of industrial coatings in mitigating risks such as N-Methyl-2-pyrrolidone (NMP) erosion and carbon black contamination, are helping to plug the gap, aiding the right first-time development of facilities.
Cutting edge manufacturing, cutting edge challenges
With global investment in electrical machinery construction, including EV battery plants, hitting £28.3 (€34) billion in 2023,1 this emerging sector represents a huge growth opportunity.
As an industry, however, it is still in its infancy. As such, manufacturers are tasked with building the protocols they need to guide the safe, effective, and sustainable development of their facilities from the ground up.
These processes need to account for the unique challenges of EV battery production. The risk of NMP erosion and carbon black disposition, for example, mean standard epoxy resin floors, widely used in the construction industry when corrosive agents are involved in the manufacturing process, may not be the best solution. In addition, the increased fire risk associated with EV battery production also requires careful consideration.
NMP erosion
In lithium-ion battery manufacturing, NMP is used as a solvent in carbon anode and lithium cobalt oxide cathode binder resins, as well as a coating and gel-polymer for separators and electrolytes.
Most coating suppliers have tested their products ability to withstand uncovered NMP, which typically evaporates within several hours. Sherwin-Williams’ ASTM D1308- standard evaluation, however, found that when the solvent is covered by foil or plastic, exposure can result in deterioration of standard epoxy flooring coating and leaching into the concrete substrate within two hours. Over time, this will prematurely breakdown the flooring, with particular weak points being the joint between stainless steel plate and concrete and resinous flooring systems, underneath drums or pallets, and around hosing or pipes that may ‘leak’ between uses.
The health and safety implications of this reaction are obvious. It poses the risk of slips and trips and obstructs the effective cleaning of facilities.
A modified urethane coating system, however, proves to be resistant to NMP for 14 full days even under the most robust of testing conditions, i.e., under glass.
In a series of tests, the surface of a panel treated with the coating was exposed to NMP for four, six, eight, ten, and twelve hours. The coating was then visually checked for swelling, gloss change, haze, and any other changes. Scratch pencil hardness was also tested, using 3H and 6H pencils, immediately and one-hour post exposure. The researchers found no visual signs of change, and all panels passed the scratch test.
Sherwin-Williams has also worked with a partner to perform on-site testing of the coatings’ NMP resistant properties with their slurry and insulation.
Together, these studies show that the modified urethane coating system could help reduce the risk of NMP exposure-related flooring deterioration and aid the effective clean-up of the substance at EV battery plants.
Carbon black slip hazard
Carbon black is a graphite-like material used in the battery slurry for both anode and cathode manufacturing. Its fine particles are deposited onto production floors during manufacturing processes and are then picked up by people and trolleys and carried throughout the facility.
This can be a huge slip risk. In fact, when Sherwin-Williams measured the dynamic coefficient of friction of epoxy floors exposed to carbon black, it did not even register a reading on the instrumentation. In other words, the floor would be more slippery than ice.
Smooth floors are essential for the easy cleaning of carbon black contamination. Yet the aggregates commonly added to resin floors to increase slip resistance can have the opposite effect, resulting in a textured surface that makes clean up challenging.
Sherwin-Williams’ specialist carbon black resistant coating, however, provides a smooth and easy-to-clean finish. What’s more, it has a slip coefficient reading of 0.72, close to the industry standard of 0.42, reducing the slip hazard even between cleanings.
Fire safety
Fire safety is, of course, an essential consideration in any facility. But Li-ion batteries can release flammable, toxic gases when failing or overheating, and these can trigger a fast-spreading, difficult-to-extinguish fire.
A typical building fire will generate heat of around 1,000°C,2 but steel, a common material for beams and pillars, will lose around 50% of its strength at just 593°C.3
Fire resistant coatings expand under heat to protect the underlying steel for as long as possible, providing a potentially life-saving a window for staff evacuation.
Quality by design
In construction, best practice involves building facilities that are easy to clean, using materials and processes that reduce risk as much as possible. There is, however, a lack of data on the best solutions to the unique challenges of EV battery facilities.
Sherwin-Williams, the first company to test its coating solutions in EV battery facilities, is proud to be part of the move to change that. We have shown that specialist coatings can reduce and mitigate the risks associated with NMP erosion, carbon black trips and slips, and battery-related fires from the start, and make for more efficient running of plants on a day-to-day basis.
As the industry matures, we will continue to test and prove the performance of our solutions, to help members of this relatively new sector embrace the opportunities – and build risk management into construction from the floor up.
Construction Dive. (2024). EV battery plant construction booms even as automakers hit the brakes. Available at: https://www.constructiondive.com/news/ev-battery-plant-construction-booms-demand/ Last accessed: 14 May 2024.
NIST. (2006). National Institute of Standards and Technology (NIST) Federal Building and Fire Safety Investigation of the World Trade Center Disaster Answers to Frequently Asked Questions. Available at: https://www.nist.gov/pao/national-institute-standards-and-technology-nist-federal-building-and-fire-safety-investigation. Last accessed: 14 May 2024 AISC. (n.d.) Available at: https://www.aisc.org/steel-solutions-center/engineering-faqs/11.2.-steel-exposed-to-fire/#9370 Last accessed: 14 May 2024
