Synthesis of edge-rich vertical multilayer graphene nanotube arrays towards high-performance supercapacitors

Molten salt-confined pyrolysis towards carbon nanotube-backboned microporous carbon for high-energy-density and durable supercapacitor electrodes

The development of a green and scalable construction of a three-dimensional (3D) hierarchically porous carbon as an electrode material for supercapacitors is promising but challenging. Herein, a carbon nanotube-backboned microporous carbon (CNT-MPC) was prepared by molten salt-confined pyrolysis, during which the salt eutectics simultaneously acted as a high-temperature reaction solvent and reusable template. Among the CNT-MPC, the CNT backbone provided a 3D conductive framework, whereas the MPC sheath possessed integrated mesopores and micropores as an efficient ion reservoir. As a result, the as-obtained CNT-MPC exhibited a high specific capacitance of 305.6 F g^-1 at 1 A g^-1, high energy density of 20.5 W h kg^-1 and excellent cyclic stability with no capacitance losses after 50 000 cycles. The molten-salt confined pyrolysis strategy therefore provides a low-cost, environmentally-friendly and readily industrialized route to develop a hierarchically porous carbon that is highly required for high-energy-density and durable supercapacitors.

Progress in supercapacitors: roles of two dimensional nanotubular materials

Overcoming the global energy crisis due to vast economic expansion with the advent of human reliance on energy-consuming labor-saving devices necessitates the demand for next-generation technologies in the form of cleaner energy storage devices. The technology accelerates with the pace of developing energy storage devices to meet the requirements wherever an unanticipated burst of power is indeed needed in a very short time. Supercapacitors are predicted to be future power vehicles because they promise faster charging times and do not rely on rare elements such as lithium. At the same time, they are key nanoscale device elements for high-frequency noise filtering with the capability of storing and releasing energy by electrostatic interactions between the ions in the electrolyte and the charge accumulated at the active electrode during the charge/discharge process. There have been several developments to increase the functionality of electrodes or finding a new electrolyte for higher energy density, but this field is still open to witness the developments in reliable materials-based energy technologies. Nanoscale materials have emerged as promising candidates for the electrode choice, especially in 2D sheet and folded tubular network forms. Due to their unique hierarchical architecture, excellent electrical and mechanical properties, and high specific surface area, nanotubular networks have been widely investigated as efficient electrode materials in supercapacitors, while maintaining their inherent characteristics of high power and long cycling life. In this review, we briefly present the evolution, classification, functionality, and application of supercapacitors from the viewpoint of nanostructured materials to apprehend the mechanism and construction of advanced supercapacitors for next-generation storage devices.