Sulfide-enhanced electrochemical capacitance of cobalt hydroxide on nanofibered parent substrate

Core-Shell Structured Cobalt Sulfide/Cobalt Aluminum Hydroxide Nanosheet Arrays for Pseudocapacitor Application

The direct synthesis of nanostructured electrode materials on three-dimensional substrates is important for their practical application in electrochemical cells without requiring the use of organic additives or binders. In this study, we present a simple two-step process to synthesize a stable core-shell structured cobalt sulfide/cobalt aluminum hydroxide nanosheet (LDH-S) for pseudocapacitor electrode application. The cobalt aluminum layered double hydroxide (CoAl-LDH) nanoplates were synthesized in basic aqueous solution with a kinetically-controlled thickness. Owing to the facile diffusion of electrolytes through the nanoplates, thin CoAl-LDH nanoplates have higher specific capacitance values than thick nanoplates. The as-grown CoAl-LDH nanoplates were transformed into core-shell structured LDH-S nanosheets by a surface modification process in Na2 S aqueous solution. The chemically robust cobalt sulfide (CoS) shell increased the electrochemical stability compared to the sulfide-free CoAl-LDH electrodes. The LDH-S electrodes exhibited high electrochemical performance in terms of specific capacitance and rate capability with a galvanostatic discharge of 1503 F g-1 at a current density of 2 A g-1 and a specific capacitance of 91 % at 50 A g-1 .

Hierarchical foam of exposed ultrathin nickel nanosheets supported on chainlike Ni-nanowires and the derivative chalcogenide for enhanced pseudocapacitance

Foamlike nickel hierarchical structures of ultrathin nanosheets supported on thin wires composed of nanoparticles are prepared by a facile one-pot synthesis via controlled nucleation and growth process. By further sulfidation, the sulfide derivative of loose porous fibrous structure shows a high electrochemical capacity for potential pseudocapacitor applications.