I prepare samples and coat them onto electrodes such as GCE, Ti sheets, or FTO. However, the coating detaches and falls into the electrolyte when I immerse them in the electrolyte (KOH, NaOH, or H₂SO₄).
I have tried several ratios for the slurry preparation:
- 75% active material, 15% PVDF, 10% Black Carbon
- 80% active material, 10% PVDF, 10% Black Carbon
However, the coating does not adhere properly in all cases and falls off into the solution.
What could be the solution to ensure the coating adheres well to the electrode and stays stable during electrochemical tests?
Hi there, Ms. Mennatullah Ghaleb;
The Doctor Blade technique is a commonly used method for coating active materials, but it may not always be the best choice for achieving optimal adhesion between the coating and the substrate, particularly if the process parameters are not fully optimized for the materials in use. Increasing the binder percentage alone is unlikely to significantly improve adhesion and may even have adverse effects on other properties, such as the electrical or mechanical performance of the coating.
To address adhesion challenges, you might consider exploring alternative coating methods better suited to your material system. Techniques such as spraying, Gravure Coating, or EPD offer unique advantages and could lead to improved results.
Also, proper surface preparation is critical for ensuring strong adhesion. Steps such as removing passive oxide layers using surface cleaning methods (e.g., chemical etching or plasma treatment) and enhancing surface roughness through mechanical or chemical means can greatly increase the effective cohesion area and improve bond strength.
For further guidance, consider reviewing resources like the Anton Paar: Battery Experts video series on YouTube. These videos provide valuable insights into material characterization and processing, particularly for battery applications, and may include practical tips for optimizing your coating and adhesion processes.
If the coating does not adhere properly in all cases and falls into the solution, it is not of uniform thickness. It can be coated if it is made uniformly of a certain thickness (e.g. 250 microns). Also, take the black carbon low and PVDF a little high. let the active material be close to these values. you should make a few trials, it may not be found immediately. another suggestion is this; make a drying process with equal thickness (do it with the help of a tool, it is not possible manually). I think you will get the right result. In this case, the coating will be able to adhere properly.
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