Synthesis of NiCo-LDH@nitrogen-doped graphene hydrogel/nickel foam composites with 3D hierarchical structure for supercapacitors

Abstract

Nickel-cobalt layered double hydroxide (NiCo-LDH)@N-GH/NF composites were prepared by a simple one-pot hydrothermal method on nickel foam (NF) substrates loaded with 3D porous nitrogen-doped graphene hydrogel (N-GH). 3D hierarchical structure has a positive role in promoting electrochemical performance. When used as supercapacitor electrodes, NiCo-LDH@N-GH/NF shows a specific capacity of 174.1 mAh·g−1 (specific capacitance of 1393F·g−1) at 1 mA·cm−2. The assembled NiCo-LDH@N-GH/NF//GH/CNT asymmetric supercapacitor (ASC) has a specific capacitance of 209F·g−1 (1 mA·cm−2). When the power density is 260 W·kg−1, the energy density reaches 63.33 Wh·kg−1.