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

Abstract

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 m² 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.