Edge elevation in battery electrode coating

Edge elevation in battery electrode coating

Tackling edge formation when coating battery electrodes

Precision and material efficiency are paramount in battery research and development, particularly with lithium-ion battery electrodes. One of the persistent challenges that researchers face is the edge elevation issue while coating thick, high-viscosity electrode layers. Edge formation, particularly side-edge elevation, also known as heavy edge, occurs when the edges of the coated substrate become elevated, creating an uneven surface that can be costly, time-consuming, and wasteful. This seemingly small imperfection can have significant repercussions throughout the battery production process, especially during the crucial stages of calendaring and cutting.

slot-die coating on foil

The costly impact of coating defects like edge elevation

Elevated edges on the coating substrate are more than just a minor inconvenience. In the cutting phase of lithium-ion battery electrode production, these elevated areas often have to be discarded, leading to substantial material waste. Given the high cost and scarcity of the materials used in battery R&D—such as lithium, cobalt, and other critical metals—this waste translates directly into increased costs and resource inefficiency. Furthermore, any inconsistency in the electrode coating can lead to performance variability in the final lithium-ion batteries, which is unacceptable in high-performance applications. This is particularly critical when producing electrodes for various battery formats, such as coin cell batteries, small pouch, and large pouch cells.

Challenges during calendaring due to heavy edge

The effects of edge elevation extend beyond the cutting phase. The elevated edges pose a significant challenge during calendaring, where the coated electrodes are compressed to achieve the desired thickness and density. The rolls used in calendaring apply pressure unevenly across the substrate, leading to inconsistent density and uneven porosity in the coated cathodes or anodes. This inconsistency can result in poor electrode distribution within the battery cell and the formation of hotspots—areas where the electrode material is denser and more conductive, potentially leading to localized overheating and reduced battery lifespan. These issues are particularly problematic in small pouch and large pouch cells, where uniformity is critical for safety and performance.
slot-die coating on foil

How FOM slot-die coaters address and improve edge quality

FOM Technologies has developed advanced roll-to-roll slot-die coating machines equipped with sophisticated, user-friendly software to overcome the challenge of edge formation and avoid coating defects like side-edge elevation. These machines allow precise control over key parameters that directly influence the deposition quality, including the leveling of the slot-die head, coating speed, and pump rate.

One of the key advantages of slot-die coating over traditional blade coating is the non-contact nature of the process. In slot-die coating, the coating head never touches the substrate. Instead, the meniscus guide—a critical component of the slot-die head—directs the slurry onto the substrate with remarkable precision. This process occurs extremely close to the substrate, essential in preventing edge elevation. By ensuring equal pressure across the lip of the slot-die head and carefully controlling the coating speed and pump flow rate, FOM Technologies’ machines achieve a uniformly distributed coating with perfectly even edges, significantly improving edge quality.

This level of control is difficult to achieve with other coating methods, such as blade coating/doctor blade, where the physical contact between the blade and substrate can easily lead to variations in pressure and, consequently, coating defects like heavy edges.

Expert support and custom solutions

At FOM Technologies, we understand that each research project is unique, and challenges can arise even with the most advanced equipment. If you ever encounter issues with elevated edges or other coating defects in your coating process, our team of experienced scientists is here to help. We offer personalized support, including live or online workshops, to help you optimize your coating parameters and achieve the best possible results with your FOM Technologies slot-die coater.

By choosing a FOM Technologies roll-to-roll coater, you’re not just investing in cutting-edge equipment—you’re gaining access to a wealth of expertise and support that will help you overcome the challenges of battery technology electrode coating, enhance edge quality, and push the boundaries of your research—whether you’re working on coin cell batteries, small pouch, or large pouch cells.

Image with BATMACHINE logo

Read more on the topic

Let’s talk about scaling your battery research

One of our experts will reach out and help you find the most suited equipment based on your needs.

 

Download the FOM Technologies Product brochure

In this brochure you will get an introduction to our products and learn about the benefits of slot-die coating such as film thickness control, film quality control. Fill in your information and click download to access the pdf.
FOM Technologies - Product brochure