Strong and light cellular silicon carbonitride – Reduced graphene oxide material with enhanced electrical conductivity and capacitive response

Abstract

Steady graphene oxide (GO) scaffolds created by direct ink writing are used to develop a silicon carbonitride (SiCN) -graphene oxide hybrid material through a preceramic polymer route. For achieving mechanically stable GO scaffolds, the drying method is critical as the ink contains about 5 wt.% of GO, 10 wt.% of polyelectrolytes and 85 wt.% of water. The liquid preceramic polymer (polysilazane type) quickly infiltrates the 3D scaffolds, under vacuum conditions, entirely covering the GO network creating a replica of the original scaffold. The hybrid cellular structure -once thermally treated for GO reduction and ceramic conversion- consists of a network of reduced GO (∼10 wt.%) embedded in an amorphous SiCN matrix following the designed architecture. The 3D hybrid structures show notable electrical conductivity (890 S m at room temperature), thermal stability and considerable strength, about 20 times higher than the single GO scaffold. The structures are tested as electrodes for supercapacitors, reaching a gravimetric capacitance of 39 F g that remains stable after 7000 charge/discharge cycles.