Semiconductor Nanowire-arrayed Electrodes for Supercapacitors

摘要

Supercapacitors (SCs) are emerging as a new class of energy storage device because they can store more energy than conventional capacitors and provide higher power than batteries. Therefore, SCs have potential applications in a number of electronic devices, including hybrid electric vehicles, laptops, cell phones and cameras. However, to meet the increasing energy demands for next-generation portable and flexible devices, the energy density of SCs should be substantially increased without sacrificing the power density and cycle life.3'5 Energy density (E) of a SC device can be calculated according to the equation E=l/2 CV~2, and increased by maximizing the device capacitance (C) and the cell voltage (V). To increase the capacitance, a large number of efforts have been devoted to the design and fabricate various nanostructured electrodes. Of various nanostractures, one-dimensional (ID) semiconductor nanowires and nanowire heterostructures hold great promise as supercapacitor electrodes. In comparison to bulk materials, these nanowires or nanowire heterostructures provide a large interfacial area between electrode and electrolyte for charge transport, and a shorten diffusion path for intercalation/de-intercalation of active species.