Single-Step, Plasma-Enabled Reforming of Natural Precursors into Vertical Graphene Electrodes with High Areal Capacitance

Graphene nanostructures possess excellent physical properties such as high surface area, good mechanical stability, and good electric conductivity, which make them attractive as electrodes for high-performance energy storage devices. However, graphene-based nanomaterials have yet to be materialized into commercial energy storage devices, mainly due to the high cost in fabrication processes and the difficulty in achieving high mass loading. In particular, the high mass loading of active materials on the electrode represents an important step toward the translation of excellent electrochemical activity seen in the microscopic regime into the practical applications. Here, supercapacitor electrodes made of vertical graphene nanosheets (VGNS) are fabricated from a range of commercially available cheese precursors via green, low-temperature, plasma-based reforming processes. Taking advantage of the fast solidification of cheese molecules and plasma matter interactions, the produced VGNS exhibit a high mass loading of 3.2 mg/cm(2) and a high areal capacitance of 0.46 F/cm(2). These results demonstrate a single-step, scalable, environmentally benign, and cost-effective approach for the transformation of natural precursors into high-quality graphene structures, which could be promising for a variety of advanced electronic and energy applications.