Laser-Graving-Assisted Fabrication of Foldable Supercapacitors for On-Chip Energy Storage

Planar supercapacitors (SCs) have been regarded as promising energy devices for on-chip electronics and they should be evaluated by areal performances due to the very limited available areas. However, these SCs usually suffer from inevitable size increase for the requirement of substrates, current collectors, and sealants. This work presents a kind of freestanding, foldable, and quasi-solid-state SCs that single SC units were stacked in the thickness direction with a common electrode to reduce their occupied areas. The foldable SCs can be fabricated in desired patterns by laser graving and their areal performances increase linearly with the assembled units. The energy density of a 5-unit foldable SC is 177.9 μWh cm^-2 at the power density of 2.78 mW cm^-2, and it outperforms most planar SCs. Therefore, this work provides a new reference to improve the areal properties of on-chip SCs from the device design aspect.