I have been trying to prepare Ketjen Black-Sulfur composite by using SBR:CMC binder for a while. But, when I coat aluminum foil with this slurry, the coating always cracks during the drying procedure. Could you give me some advice to improve this?
How do you apply the coating?
What is the particles size of the Ketjen Black-Sulfur.
You can manage the rate of drying( 5 deg/min) as a first step.
Are you drying at room temp? We encountered problems when the coating is too thick or when the solid:solvent ratio has to be improved (you might use too much water). You can also try to slow down the evaporation by partly covering your cast with a plastic box or sth similar. Anyhow, I wouldn't recommend to increase the temp. befor it appears dry.
Nils
Could you plz share additional details? I recommend you to change the ratios. And, try to make your electrode thinner. Besides, you should think about some strong chemical bonds between the components. My recommendation is 150 C, around 3 h, and vacuum drying.
I would like to thank all of you for sharing your valuable opinions. At last, I made the homogeneous coating, but unfortunately I got this by using %20 binder which is very high. And when calculated, active material is very low; 0.6 mg/cm2.
@Mohammed Gabara I am using doctor blade to coat Al foil. I don't know the particle size of Ketjen Black. I dry coating at room temperature.
@Nils Wagner Yes, I dry at room temperature. Yes, your point is very true; water ratio was very high at that time. Now, for me the question is how I can provide thick coating? :) Do you have any idea to provide thicker coating?
@Masoud Nazarian-Samani In fact, now I am trying to make thicker coating to get more active material. Thank you so much.
What is the solvent that u r using? If it is NMP(or whatever), then try to add it slowly under stirring condition. Make sure that the slurry is viscous enough. If u add more solvent, then the slurry becomes dilute which will generate cracks after drying. If u add less solvent (only required amount), then u can automatically coat thicker electrodes using doctor blade. Also binder content is very much important. First, add binder to solvent and dissolve it then add rest of the materials. Hope it helps!
Dear Bolloju,
I am using pure water as solvent. And thank you so much for your suggest, I will try it.
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