Controlled synthesis of zinc cobalt sulfide nanostructures in oil phase and their potential applications in electrochemical energy storage

A unique controlled synthesis of zinc cobalt sulfide nanostructures is obtained by a facile oil phase approach. Nanoartichokes composed of self-assembled nanosheets and nanoparticles have been fabricated by using different sulfur sources. The application of such nanomaterials is demonstrated as electrodes for supercapacitors and lithium-ion batteries. Serving as lithium-ion battery electrodes, the Zn_xCo_1-xS nanoartichokes deliver a higher specific capacity of 750 mA h g^-1 during the 100th cycle as compared to only 220 mA h g^-1 for nanoparticles. In supercapacitor tests, the Zn_xCo_1-xS nanoartichokes possess an improved specific capacitance (486.2 F g^-1 at a current density of 2.0 A g^-1) and excellent cycling stability (retaining 86.4% after 2000 cycles), both of which are much higher than those of nanoparticles (e.g. 406.7 F g^-1 and 73.3%). This effective nanostructure design of ternary transition metal sulfides could provide a promising method to construct high-performance materials for energy and environment applications.