Selective vacuum filtration-induced microelectrode patterning on paper for high-performance planar microsupercapacitor

Graphene-based microsupercapacitors (mSCs) as important micro-power sources for miniaturized electronic devices have been a fascinating research topic. However, the large specific surface area of graphene is not fully exhibited due to the π-π stacking of graphene nanosheet in these graphene-based mSCs system fabricated by previously reported methods. Here, we propose a new method to fabricate the compact, flexible and all-solid-state graphene hydrogel-based mSC (GH-mSC) by combing paper chip with selective vacuum filtration, which allows the fabrication of mSCs with different sizes and shapes. The stack capacitance value of GH-mSC is 2.51 F cm⁻³ and the CV curve still keep quasi-rectangular even at a very high scan rate of 50000 mV s⁻¹. The GH-mSC delivers acceptable energy densities of 0.223 mW h cm⁻³ and power densities of 0.024 W cm⁻³, which is better than electrolytic capacitor. Further, the GH-mSCs exhibit superior long-time cycling stability and good flexibility. More importantly, the mSC on paper chips allows easy scaling up of capacitance and output voltage by simply fabricating several mSCs on a plane or both sides of a paper and then connecting in parallel or series. These characteristics suggest that GH-mSCs are promising as power sources.