Freestanding Micro-Supercapacitor With Interdigital Electrodes for Low-Power Electronic Systems

With the rapid development of miniaturized multi-functional systems, micro-energy-storage devices have drawn increasing attention due to the importance of power supply. In this paper, a novel fabrication for freestanding solidstate micro-supercapacitors (MSCs) has been proposed and developed by combining electrolyte transferring with laser patterning process. Typical freestanding MSC is composed of interdigital carbon nanotube/nanofibers as active material employed by laser patterning process, PVA/H
₃
PO
₄
as both the solid-state electrolyte and the flexible substrate, and gold layer as the current collector. With the in-planar electrode and electrolyte-substrate layout, the dimension of the MSC could be greatly decreased without excess substrate. Taking advantage of electrospinning nanofibers with large surface area and carbon nanotubes with high conductivity, we optimize the line-width (200 μm) of the interdigital finger of the MSC, which exhibits high areal capacitance (15.6 mF/cm
²
) and excellent cycling stability. With the serial design, the working range of MSC units could be greatly enhanced in wearable devices and low-power electronic systems. Therefore, such flexible MSC is a promising candidate to satisfy the requirements of miniaturized energy systems.