Stamp-assisted flexible graphene-based micro-supercapacitors

The rapid growth of portable and wearable electronics have greatly stimulated simplified fabrication of energy storage devices, from which micro-supercapacitors (MSCs) are an ideal power source, due to high power density and long lifetime. However, the development of a simple and cost-effective procedure towards the fabrication of high-performance MSCs is still a challenge. To this end, here we report a self-patterned stamping process through pre-designed patterns (Fractal & Interdigital) on parafilm (R) coated polyethylene terephthalate (PET) substrate for the fabrication of a flexible and planar MSC. The imprinted patterns on parafilm (R) are filled by graphene oxide (GO)/carbon aerogel/MnO2 hybrid paste as a binder and additive-free active material, followed by GO reduction through a safe, low cost, and effective procedure using nascent hydrogen. In contrast to the hydrazine based reduction method, nascent hydrogen affords the integrity and stability to the active material without any peeling off from the substrate, with low ohmic resistance. The prepared MSCs display large capacitance and energy density of 8.7 mF cm(-2) (43.66 F cm(-3)) and 6 mWh cm(-3) for Interdigital electrode and 14.2 mF cm(-2) (71.34 F cm(-3)) and 9.9 mWh cm(-3) for Fractal electrode, respectively. Furthermore, the MSC displays capacitance retention of 85% after 25,000 cycles. The presented procedure is a simple and cost-effective strategy towards the fabrication of flexible MSCs with state-of-the-art performance.