Nanoneedle-decorated NiCo-layered double hydroxide microspheres tuned as high-efficiency electrodes for pseudocapacitors

Designing hierarchical structures is of importance to enhance the electrochemical performance of electrode materials for energy storage devices such as supercapacitors. We herein report nanoneedle-decorated NiCo-layered double hydroxide (NiCo-LDH) microspheres used as electrode nanomaterials for pseudocapacitors. The nanoneedle-decorated NiCo-LDH microspheres are tuned by varying the amounts of an alkaline agent (NH4F) that is observed to increase the thickness and rigidness of nanoplatelets, as well as the coverage of nanoneedles. The nanoneedle-decorated NiCo-LDH microspheres, optimized by using 13 mmol NH4F, exhibit the largest specific surface area of 127.8 m(2) g(-1) and display the best electrochemical performance with a specific capacitance of 1644 F g(-1) at a current density of 1.0 A g(-1), as well as a good specific capacitance retention of 93.8% after 1000 cycles at a high current density of 10 A g(-1). The results may open up a possibility of producing controllable hierarchical LDH nanostructures as promising electrode nanomaterials for pseudocapacitors.