Growth of carbon nanosheets on carbon nanotube arrays for the fabrication of three-dimensional micro-patterned supercapacitors

Abstract

Micro-supercapacitors provide high peak power, long cycle life, and high charge/discharge rates for practical applications in microsystems. However, current micro-supercapacitors generally suffer from low energy density and complicated fabrication process. Here, we report carbon nanosheet (CN) selectively grown on carbon nanotube (CNT) patterns as three-dimensional hybrid electrodes for high-performance micro-supercapacitor applications. The growth mechanism is revealed that CNs prefers to grow on CNT surface rather than on SiO2 substrate due to the high binding energy of carbon atom absorbed on CNT surface. The symmetric all-carbon CN/CNT micro-supercapacitors exhibit ultrahigh areal capacitance of approximately 110 mF cm−2 at a current density of 0.3 mA cm−2, outstanding long-term cyclic stability (≈7% loss of initial capacitance after 10,000 cycles). Furthermore, flexible microsupercapacitors are achieved by peeling off microelectrodes using H3PO4/PVA electrolyte and showing high functional flexibility (capacitance loss less than 9% after 100-cyclic bending tests). The outstanding electrochemical performance and functional flexibility of present micro-supercapacitors show great potential applications in smart and miniaturized electronic devices.