Dear Moonyoung. 

First of all, what is a solid to solvent ration of your suspension? It seem like you have to many solvent. The second problem I see is a large species of your active material. Try to decrease the particle size. It can improve the quality and homogeneity of the suspension. What is the solvent you use? Do you use some surfactant agent in order to improve the sticking of the slurry to the Cu/Al?

Describe your active material and conductive agent, particle sizes, specific surface areas. Then, you can get answers. A question is always more important than an answer. Using PVdF means you must be using NMP.

While using PVDF, you can use also cyclopentanone solvent.