If you are talking about electroactive materials for Li ion batteries, the regular proportions between active material, conductive carbon and PVDF (80:10:10% w/w, using a proper solvent) can easily allow you to obtain 5-6 and even 7 mg/cm2 of active material. just by making the slurry thick enough over the current collector (Al or Cu) but if you get to much active material and an electrode way to thick, you may get end up with a certain proportion that would no react due to the electrolyte inability to reach the very center of the electrode bulk