In this paper, a printed separator is proposed. With a printed separator, the battery and supercapacitor manufacturing process can be improved greatly since the electrode is also manufactured by printing. Futhermore, on-demand printed battery or supercapacitor can be easily manufactured, which are required in the wearable device industries.
First, we have made a cellulose nano fiber ink from the purified cellulose powder. The powder is mixed with IPA and processed in the high pressure homogenizer to get a colloid ink. The more we process the solution in the homogenizer, the finer fiber we get. In this paper we have used an ink containing few tens nm thickness fiber.
To make a membrane from the colloid ink, we have used the Musashi dispenser which is adequate to print high viscous ink. A drop-on-demand printing method is used since the colloid ink cause clogging in a continuous printing mode. In the drop-on-demand mode, basically, three processing parameters directly affect the membrane thickness; dispensing pressure, dispensing time, and drop spacing. Among them, the drop spacing is the easiest parameter to control the membrane thickness.
Finally, all printed supercapacitor has been manufactured. On a aluminium foil, activated carbon is printed using screen printer and the cellulose nano fiber ink is printed using dispenser. The final separator thickness is about 14 µ. The capacitance of the capacitor with the printed separator is about 184 F/g, which is slightly larger than the one with the commercial separator.
Fig.1 Cyclic voltammetry for the capacitor with commercial and printed separator