Ultrafast planar microsupercapacitor based on defect-free twisted multilayer graphene

One of the major challenges in miniaturization of modern electronic components is the inability to replace bulky filtering capacitors with high capacitance yet retaining filtering efficiency at frequencies higher than 100 Hz. Though planarly integrated microsupercapacitors offer high capacitance, their frequency response is limited due to surface defects. In this article, we report the fabrication of a planar microsupercapacitor using twisted multilayer graphene (tMLG) exhibiting an ultrahigh-frequency response in the order of 10,000 Hz, highest reported till date for any supercapacitor. The cyclic voltammetry could be performed at scan rate as high as 10000 V/s producing near rectangular CV curves indicative of double-layer capacitive behavior of the device with excellent stability over thousands of cycles. The devices exhibited the specific capacitance in the range of 0.01-0.1 mF/cm(2), stack capacitance of 2-20 F/cm(3), energy and power densities of 0.5-1.5 mWh/cm(3) and 50-2000 W/cm3, respectively, comparable to the best reported graphene-based microsupercapacitors.