Evaporative assembly of graphene oxide for electric double-layer capacitor electrode application

Graphene reduced from graphene oxide (r-GO), a potentially low-cost way of obtaining a large quantity of graphene, faces many challenges and concerns, including the challenge to retain nanoscale properties after processing and the associated environmental, safety and health concerns. This study explored the method of processing graphene oxide (GO) into microparticles by spray drying as an intermediate step for fabricating electric double-layer capacitor electrodes. We prepared GO microparticles by spray drying an aqueous solution of GO and then thermally reduced GO to r-GO. The r-GO microparticles, with a size of ~. 1-2. μm, had a corrugated surface morphology with alternating grooves and ridges, a microstructure resembling that of crumpled paper. Electrochemically, r-GO compared well to nano-sized activated carbon which was used as a reference. Furthermore, r-GO retained most of its specific capacitance at high current densities, mostly due to the corrugated surface morphology of r-GO microparticles. The results suggest that spray drying, a scalable manufacturing method, is a simple and promising way of processing GO for EDLC electrode application. Future research should focus on improving the surface area for high specific capacitance by mitigating the stacking of GO during spray drying.