Hierarchical design of NiCo-LDH NFs@Co(OH)2 nanosheets supercapacitor electrode material with boosted electrochemical performance

Abstract

Layered double hydroxides (LDHs) have been considered as excellent pseudocapacitive electrode materials for supercapacitors because of their controllable layered structures and high theoretical specific capacitances. However, poor conductivity and shortage of effective active sites hinder their applications. Herein, in order to boost the capacitance performance, an electrode material composed of NiCo-LDH nanofibers with cobalt hydroxide (Co(OH)2) nanosheets firmly anchored to or uniformly immobilized onto NiCo-LDH nanofibers surface is constructed. The material architecture takes advantage of superior capacitive activity from Co(OH)2 with good electronic conductivity and dispersibility over the surface of NiCo-LDH nanofibers. The merits based on the elegant synergy between NiCo-LDH nanofibers and Co(OH)2 nanosheets induce an outstanding specific capacitance of 858.9 F/g at a current density of 0.5 A/g. With the current density increasing from 0.5 to 10 A/g, the specific capacitance retention is 67.3%, indicating a good rate capability. Furthermore, the electrode material exhibits a capacitance retention of 83.7% after 2000 cycles at 10 A/g. These excellent electrochemical properties are due to the hierarchically designed structure and the cooperative contributions of NiCo-LDH nanofibers and Co(OH)2 nanosheets, which shows great potential for energy storage applications.